Administrative and Support Services (U.S.) — NAICS 561

A Histometrics rollup primer for a general investing audience — relevant to both public-market and private investors. NAICS (the North American Industry Classification System) is the U.S. government's standard scheme for grouping businesses by activity. Code 561, Administrative and Support Services, is a three-digit "subsector" that sits above eight four-digit "industry groups" (5611–5619). This page synthesizes the eight already-written child primers plus our ground-truth federal statistics for this level. Figures are reported facts unless the wording marks them as projections or judgments.[1]

1. Overview

Administrative and Support Services is where the American economy buys the work it would rather not do itself. Almost everything inside NAICS 561 is a business selling a support function — staffing, cleaning, security, admin, travel booking, collections, call answering — to other organizations on a contract or fee basis, so those organizations can concentrate on their own core work. It is the outsourced back office, front desk, loading dock, and security post of the whole economy.

On paper it is one of the largest subsectors in the federal statistics: roughly $1.21 trillion in 2022 receipts and about 13.0 million counted employees.[1] But it is not one market. It is eight loosely related service industries the Census Bureau filed together because each is business-to-business support work — and the honest, distinctive story here is the contrast across those eight children: which are large, which are growing, which are shrinking, who owns them, and how differently each one actually makes money. That contrast is the whole reason to look at 561 as a rollup rather than reading the children one at a time, and it is the subject of Section 2.

Three facts frame everything below. First, the subsector is enormous but lopsided: one child (employment services) alone is ~46% of the revenue and ~60% of the jobs, while the smallest (facilities support) is barely 3%.[1] Second, it is capital-light and labor-heavy almost everywhere — payroll is ~60% of receipts at face value — so returns come from scale, utilization, retention, and consolidation, not from pricing power. Third, the children run on genuinely different profit engines — labor arbitrage, recurring-subscription annuities, data toll-collection, distressed-debt investing, commission take-rates, franchise-media — so no single valuation lens fits the level, and how an investor buys in depends entirely on which child they mean.

2. What's inside — the eight children and how they differ

The single most useful thing this rollup adds is the comparison. First the quantitative shape (all figures from our ground-truth federal file; receipts and concentration are 2022 Economic Census ("EC"), employment is 2023 County Business Patterns ("CBP") — two programs from different years, so do not divide one by the other to derive a true margin):[1]

CR4 = combined revenue share of the four largest firms; HHI = Herfindahl-Hirschman Index, a standard 0–10,000 concentration gauge where below 1,500 is "unconcentrated" under U.S. antitrust guidelines. HHIs are rounded here; exact child values appear in the child primers.[2][3][4][5][6][7][8][9]

And here is how the eight differ on the axes an investor actually cares about:

The headline contrasts:

• One child is nearly half the revenue and most of the jobs. Employment services (5613) is ~46% of receipts and ~60% of employment — because staffing agencies and professional employer organizations (PEOs — firms that become the legal employer-of-record for a client's staff) count the millions of placed and co-employed workers on their own payrolls. Those people physically work in factories, hospitals, and warehouses but are booked here, at their employer of record. Read that 60%-of-jobs figure with care: it is why the subsector nominally has the largest employment footprint in the economy while much of that headcount is really other industries' labor, statistically re-homed [4].

• Revenue rank is not headcount rank. Building services (5617) is the second-biggest child by revenue but employs far fewer than employment services; travel arrangement (5615) is 5.7% of receipts on just 1.4% of the jobs, because a global distribution system or a ticketing platform is a handful of high-value technology workers, not an army [6][8]. The subsector spans people-heavy trades (cleaning, guarding, call centers) and asset-light platforms (reservation systems, credit bureaus) that could not be more different per worker.

• "Concentration" is nearly meaningless at this level and everything inside the niches. The subsector HHI is 25 and its CR4 just 7.8% — statistically "unconcentrated" to the point of near-perfect competition.[1] But that is an aggregation artifact: pooling eight industries that never compete into one $1.2 trillion denominator shrinks every firm's share. Genuine competitive concentration lives inside the children and, deeper still, inside their niches — a three-firm credit-bureau oligopoly (inside 5614), a near-monopoly in event ticketing (inside 5615), a two-firm pest-control duopoly at the top (inside 5617). Read 25 as "this is a bundle of separate markets," not "one giant free-for-all."

• AI cuts the subsector in two. Generative artificial intelligence (AI) is an existential threat to the children that sell the billed human hour — call centers and document prep (in 5614), commodity recruiting and light-industrial temp (in 5613), routine office admin (5611), and at the margin even guards (video analytics can replace posts, in 5616). It is mostly a tailwind for the data and platform assets — credit bureaus, alarm-monitoring analytics, reservation systems. Same subsector, opposite exposures.

Where the code boundaries sit. Each child excludes its neighbors, and the subsector as a whole excludes the work organizations do in-house (a bank's own collections, a hospital's own guards, a retailer's own cleaners are booked in their industry, not here) and the waste-management-and-remediation subsectors (562) that share sector 56 with 561.[10] The federal figures below count only what the codes narrowly capture.

3. How big it is (this level's rollup figures)

Our federal ground-truth statistics for the combined subsector, NAICS 561. Receipts, firm counts, and concentration are 2022 Economic Census; establishment, employment, and payroll counts are 2023 County Business Patterns — two programs from different years, so do not stack them into one income statement.[1]

The rollup reconciles almost exactly — a strong confidence check. The eight children sum to this level essentially to the unit: establishments (36,864 + 9,019 + 56,173 + 29,171 + 15,704 + 26,992 + 227,045 + 20,809 = 421,777) and employment (550,384 + 283,836 + 7,790,831 + 673,396 + 186,812 + 1,011,407 + 2,156,568 + 307,764 = 12,960,998) match the level file precisely; receipts sum to ~$1,209.2 billion and payroll to ~$727.4 billion, each reconciling to within rounding.[1][2][3][4][5][6][7][8][9] The only line that does not add up is the firm count: the children sum to 360,603 versus the level's 359,824, because ~779 companies operate under more than one four-digit code and are counted once at the subsector level but in each group they touch (~0.2%). That tight additivity confirms the level file and the child files are drawn from the same underlying census.

What the numbers reveal — but read them carefully:

• A labor-driven subsector, but the headline overstates it. Payroll is ~60% of receipts at face value — the signature of a wage-based service economy. But that ratio is inflated by employment services (5613), whose payroll line includes the pass-through wages of ~7.8 million placed and co-employed workers who physically work elsewhere.[4] Strip 5613 out and payroll is ~39% of the remaining ~$651 billion of receipts — still labor-heavy, but not two-thirds. Read 561 as two things stapled together: a vast low-wage labor pool and a much smaller set of asset-light, high-value platforms.

• Concentration is lower at the subsector than in most of its children. The level HHI of 25 sits below six of the eight children (all but the two most-fragmented, office admin at 7 and building services at 17).[1] That is arithmetic, not a market fact — pooling eight non-competing industries dilutes every firm's share. No one dominates 561 because 561 is not a market anyone competes in.

• This is overwhelmingly a small-business subsector. Average receipts per firm are ~$3.4 million and the median firm is far smaller; every child's typical operator sits below its Small Business Administration size standard (which range from roughly $19 million to $47 million of average annual receipts across the children).[2][3][8] The great majority of the 359,824 firms qualify as small businesses.

Undercount caveat — the $1.2 trillion is an employer-only floor. These are employer counts: CBP and the Economic Census largely omit nonemployer businesses (the self-employed and firms with no paid staff), and small/individual ownership dominates several children — hundreds of thousands of solo landscapers and one-truck route operators (5617, 5619), home-based travel advisors (5615), solo private detectives and mobile locksmiths (5616), one-person admin and résumé shops (5611, 5614). Landscaping alone had roughly 434,554 nonemployer businesses in 2023, a tail larger by count than the entire employer building-services group [8]. Two further scope effects push the same way: in-house ("captive") operations are excluded by definition, and much household-name activity is booked under adjacent codes. Our ground-truth file for this level carries no nonemployer total, so none is stated here. And the top line is not apples-to-apples: some children book gross revenue swollen by pass-through (temp wages, PEO billings), while travel agencies book only their commission, not the trip value. Treat $1.2 trillion as the visible employer core of a much larger support-services economy, not its full weight.

4. Investable universe (where value concentrates across the children)

For a public-market investor the defining feature of NAICS 561 is that there is no pure-play, no fund, and no clean ticker for the subsector — and, oddly, public access runs partly inverse to size. The two biggest children by revenue (employment services and building services) are dominated by private ownership and small operators, while several smaller children offer the cleanest listed pure-plays. For a private investor the opposite holds: nearly every child is a target-rich roll-up field, and this is collectively one of the deepest small-business M&A pools in the economy.

(Company names below are thematic orientation, not quotes or recommendations; tickers, yields, and multiples belong to the how-to-invest section and the child primers. Most listed names report diversified segments, not a clean NAICS line, so treat them as proxies and underwrite the relevant net economics — not consolidated revenue swollen by wage pass-through or unrelated businesses.)

Where clean public quality concentrates (a few corners, mostly in the smaller children):

• Credit bureaus — the level's single cleanest quality play (inside 5614). Equifax (NYSE: EFX), TransUnion (NYSE: TRU), the scoring franchise FICO (NYSE: FICO), and Experian (London: EXPN) are large-cap, high-margin "data toll booth" businesses that behave nothing like the rest of the subsector [5].
• Pest control (inside 5617). Rollins (NYSE: ROL, Orkin) and Rentokil (Terminix) are the scaled recurring-revenue pure-plays — the best public access anywhere in building services [8].
• Alarm monitoring and cash logistics (inside 5616). ADT (NYSE: ADT) and Alarm.com (Nasdaq: ALRM) are the near-pure-plays in electronic security; Brink's (NYSE: BCO) is the one clean listed large-cap in the people-heavy cash-in-transit trade; First Advantage (Nasdaq: FA) is effectively the only listed background-screening pure-play [7].
• PEOs (inside 5613). TriNet (NYSE: TNET) and Insperity (NYSE: NSP) are the clearest pure-plays in the whole employment-services group, with ADP and Paychex as lower-volatility payroll/PEO giants [4].

Where public exposure is cyclical or diversified (the bigger, more contested corners):

• Staffing (inside 5613) — a dozen cyclical listed names (ManpowerGroup, Kelly, AMN Healthcare, Robert Half, Korn Ferry), though the largest U.S. staffing firm, Allegis, is private [4].
• Facilities and building services (5612, 5617) — ABM (NYSE: ABM) and EMCOR (NYSE: EME) for the closest U.S. facility/building-services exposure; BrightView (NYSE: BV) as the one listed landscaping pure-play [3][8].
• Call centers (inside 5614) — Concentrix (Nasdaq: CNXC), TTEC, TaskUs, and French-listed Teleperformance, trading at depressed valuations after an AI-driven sell-off, plus the debt buyers Encore (Nasdaq: ECPG) and PRA Group (Nasdaq: PRAA) [5].
• Travel distribution (inside 5615) — the mega-OTAs Booking (NYSE: BKNG) and Expedia (Nasdaq: EXPE), the reservation backbone Sabre (Nasdaq: SABR), and ticketing via Live Nation (NYSE: LYV) [6].

Where value is private or non-buyable: contract guarding (5616's biggest activity — Allied Universal and GardaWorld are private, with a possible Allied Universal 2026 initial public offering the marquee catalyst); healthcare management-services organizations and fund/corporate administrators (5611); most tour operators and corporate travel management companies (5615); trade-show brands and co-packers (5619); and the government-run convention-and-visitors bureaus (5615), reachable only through municipal hotel-tax bonds [2][6][7][9].

Bottom line: listed quality concentrates in a handful of corners — credit data, pest control, monitoring, cash logistics, PEOs — while the bulk of the subsector's $1.2 trillion, including its two largest children, changes hands privately.

5. How the money works

Strip away the eight labels and the subsector runs on a small number of distinct engines. Knowing which one you are looking at tells you the cyclicality, the capital intensity, and the right valuation lens.

• Sell hours (labor arbitrage) — the dominant model. Most of the subsector bills a unit of human work — a staffing hour, a cleaned square foot, a guard-shift, an agent-call, a packed parcel, an admin task — above the fully-loaded cost of the person doing it, times how busy they are kept. The levers are the same everywhere: utilization/occupancy, attrition and re-hiring cost (turnover is chronically high, above 50% in guarding and cleaning), billable-hour mix (complex, regulated work bills more), and route/branch density (packing more stops or seats into each worker's day). Margins are thin — mid-single-digit net is common, ~1% at the janitorial leader [4][8]. This describes 5611, 5612, 5617, most of 5616 (guards), the temp side of 5613, the call-center side of 5614, and the packaging/route side of 5619.

• The recurring annuity (subscription). Some of the best cash flow in the subsector comes from contracted, renew-for-years revenue: alarm monitoring priced and valued on Recurring Monthly Revenue (RMR — the sum of contracted monthly fees, where a book trades at 25–50× monthly RMR and low churn is the whole game), recurring pest and cleaning routes, and auto-club and timeshare-exchange memberships (in 5615) [6][7][8]. Switching friction and predictability make these the assets buyers pay up for.

• Sell the same data twice (the toll booth). Credit bureaus (in 5614) are the outlier: lenders contribute borrower data for free, the bureau sells it back per report at near-zero marginal cost, and incremental margins run to the high tens of percent [5]. This is the one durable pricing-power model in the subsector, and it is why one child earns several times the revenue-per-worker of the rest.

• Fee, spread, and float (intermediation). Placement agencies earn a one-time fee (in 5613); tour operators and staffing firms earn a spread funded partly by customer deposits or by billing clients after paying workers (float and working capital); PEOs add an insurance spread by pooling thousands of workers; debt buyers (in 5614) purchase charged-off receivables and collect for their own account, valued like a specialty-finance investor on estimated remaining collections [4][5][6].

• Franchise-media and tax-funded civic (the niche exceptions). Trade-show organizers (in 5619) run a high-margin franchise-media model — the #1 show in a vertical is a local monopoly with negative working capital [9]. Convention-and-visitors bureaus (in 5615) earn no profit at all; a hotel-tax slice funds destination marketing [6].

The unifying trait is that most of 561 is a capital-light, labor-based, recurring/contract service business whose top line overstates the money actually kept, and whose returns come from scale, efficiency, retention, and buy-and-build consolidation rather than organic pricing power. The exceptions that do have pricing power — credit bureaus, dominant trade shows, ticketing, monitoring annuities — are precisely where durable value concentrates. Standard factory "capacity utilization," regulated-utility "rate base," REIT "funds from operations," and mining "all-in sustaining cost" lenses do not fit this subsector; revenue-per-productive-hour, contribution-margin-per-seat, RMR multiples, and enterprise-value-to-EBITDA (earnings before interest, taxes, depreciation, and amortization) do. Our federal file reports no subsector-wide margin, growth rate, or total addressable market, so none is stated.[1]

6. Demand drivers

Because the children answer to different forces, the subsector has no single demand driver — but a few cross-cutting themes tie most of it together.

• The make-versus-buy (outsourcing) decision — the master driver. Nearly every child exists because organizations decide a support function is non-core and cheaper to buy than build. Roughly half of janitorial labor is still in-house, a long runway to convert; the same logic drives staffing, admin, security, and building services [4][8]. Corporate cost pressure and recessions often push more volume out the door to outsourcers, making parts of the subsector counter-cyclical to their clients' budgets.

• The labor market and the business cycle. Employment services (5613) is a leveraged bet on hiring confidence, with temp help a classic leading indicator; travel arrangement (5615) rides discretionary and corporate travel; parts of business support ride client budgets [4][6]. Rising wages mechanically lift the pay-linked fee bases (staffing fees, PEO service charges, guard bill rates) even as very steep wage growth can delay hiring.

• The credit cycle. Collection agencies and credit bureaus (in 5614), plus auto repossession (in 5619), track lending and delinquency — record U.S. household debt expands the scorable and collectible pool [5][9].

• Compliance complexity. Thickening payroll-tax, benefits, wage-and-hour, data-privacy, and safety rules push admin, HR, screening, and collections work to specialists who can absorb the compliance load [2][4].

• Construction and the AI-driven data-center build-out. Facilities support, security, and building services all track a growing, more technically complex building stock led by data centers and reshored manufacturing [3][7][8].

• AI, cutting both ways. It destroys demand where it deflects calls, drafts documents, or automates admin, and it creates demand where cheap automation pulls in new buyers or where enterprises need help deploying and supervising the technology; for the data children it is mostly additive [5].

7. Regulation

There is no single regulator or license for NAICS 561; oversight follows the activity performed and the data handled, and intensity varies enormously across the children — which is itself a diligence signal. A common base of employment law (the Fair Labor Standards Act; anti-discrimination rules enforced by the Equal Employment Opportunity Commission; Occupational Safety and Health Administration standards) runs under all of it, and then each child adds its own regime:

• Consumer-finance rules — the Fair Debt Collection Practices Act and the Fair Credit Reporting Act (FCRA) govern collections, credit bureaus, and background screening (in 5614 and 5616), among the most heavily regulated activities in the country [5][7].
• Co-employment and PEO rules — joint-employer liability, the IRS Certified PEO program, and state agency licensing shape employment services (5613) [4].
• Federal contracting rules — the McNamara-O'Hara Service Contract Act sets prevailing wages on covered federal work, central to base-operations facilities support (5612) and government guarding (5616) [3][7].
• Activity-specific regimes — pesticide law (the Federal Insecticide, Fungicide, and Rodenticide Act) for pest control (5617); the Telephone Consumer Protection Act for call centers (5614); anti-money-laundering rules for armored car (5616); seller-of-travel and antitrust for travel (5615); FDA good-manufacturing-practice rules for pharmaceutical co-packing (5619); and immigration and the H-2B visa cap for landscaping and janitorial (5617) [5][6][8][9].

Common thread: firms in 561 are generally more exposed to the rules they administer on clients' behalf — and to the sensitive payroll, financial, health, and personal data they hold — than to any single license on themselves. In every child, compliance quality is simultaneously a competitive moat (it keeps sub-scale entrants out) and an uncapped liability (an FCRA class action, an anti-money-laundering penalty, a wrongful-repossession or use-of-force claim, or a data breach can be existential for a small operator). At the margin, tightening rules favor scaled operators who can absorb the cost.

8. Consolidation

The subsector's structural signature is a barbell: extreme fragmentation at the base (359,824 firms, CR4 7.8%, HHI 25) with durable value consolidating at the top of each child.[1] That gap — between fragmented supply and the scale advantages available to leaders (route/network density, purchasing power, software, data, compliance capacity, and a valuation premium on recurring revenue) — is exactly what fuels relentless private-equity buy-and-build across virtually every child. The mechanics differ:

• Route-density roll-ups in pest control, landscaping, and building services (5617), monitoring account-books (5616), and route trades inside 5619 — bolt a nearby operator onto an existing route and the density is immediately accretive [7][8][9].
• Scale-and-capability roll-ups in facilities support (5612), call-center BPO (5614), and staffing/PEO (5613) — where the strategic logic has shifted from buying scale (more seats or bodies) toward buying capability (software, domain expertise, AI platforms, and insurance-buying power) [3][4][5].
• Show-brand and platform acquisition in trade shows and co-packing (5619) [9].
• Cross-boundary bundling — integrated facilities management (running the whole building) and integrated security (officers plus cameras plus monitoring) increasingly blur the lines between children as global platforms assemble one-vendor offerings [3][7].

Public consolidators exist in a few corners (Rollins/Rentokil in pest, ABM in facilities, the credit-bureau oligopoly, ADT in monitoring), but most consolidation happens privately and will keep showing up as niche platforms rather than as rising concentration at the 561 level — because pooling non-competing industries can never raise the subsector's measured HHI no matter how much roll-up occurs within a niche.

9. Risks

• AI substitution and price deflation — the defining risk for the labor half. Live deployments already replace agents, drafters, and routine admin at scale (public markets have repriced call centers severely), and commodity recruiting, temp, and clerical work sit directly in the path [4][5]. The data, annuity, and franchise assets are largely insulated and may benefit — but a subsector that is ~60% labor by payroll has real exposure.
• Cyclicality and end-market concentration. Employment services is a high-beta bet on hiring; travel and parts of business support ride discretionary spend and the credit cycle. Building services, pest, and monitoring are more defensive. Losing or repricing one large contract can strand facilities and trained staff in any labor child [4][6].
• Confusing revenue with value. Much of the subsector's top line is wage-and-insurance pass-through (temp, PEO) or commission (travel), so firms can grow gross revenue while net economics stagnate — the single most common analytical trap here [4].
• Labor cost, turnover, and immigration exposure. Wage inflation, chronic turnover, and enforcement risk (E-Verify, the H-2B cap) hit the people-heavy children hard, on thin margins with little cushion [8].
• Regulatory drift and litigation. Co-employment and joint-employer standards, equal-pay-for-temps laws, AI-hiring audits, consumer-finance rules, pesticide bans, and data-privacy mandates all raise compliance cost and can narrow the very cost advantages these firms sell.
• Data-security and privacy liability. Screeners, credit bureaus, monitoring firms, and payroll/PEO operators hold highly sensitive data; a serious breach is existential.
• Roll-up and leverage risk. The PE platforms that own the best private assets carry meaningful, often undisclosed debt; integration missteps or rising rates strain the most levered operators.
• Measurement risk. Employer-only federal data understate the nonemployer- and in-house-heavy reality, and mix gross and net receipts across children — so both the true size and the true fragmentation of the subsector are hard to pin down, and third-party "market size" figures routinely blur these codes with adjacent ones [1].

10. How to invest and the outlook

Public routes — narrow, uneven, and assembled child-by-child. There is no listed pure-play, ETF (exchange-traded fund), or REIT for NAICS 561; you build exposure to the corners you want. The cleanest, highest-quality listed exposure sits in a few children: credit bureaus (EFX, TRU, FICO, Experian) for durable data toll booths; pest control (ROL, Rentokil) for defensive recurring-revenue compounders; alarm monitoring (ADT, ALRM) and cash logistics (BCO) in security; and PEOs (TNET, NSP) plus ADP/Paychex for the defensible end of employment services. Higher-beta, contrarian, or diversified public exposure runs through cyclical staffing equities, depressed call-center operators (CNXC, TTEC, TEP) and the debt buyers (ECPG, PRAA), facilities and landscaping names (ABM, EME, BV), and travel distribution (BKNG, EXPE, SABR, LYV). Because most listed names are diversified, foreign, or straddle children, do not compare multiples mechanically — judge each on the net economics attributable to the activity, on recurring-revenue quality and retention, and on utilization, leverage, and litigation reserves.

Private routes — where most of the subsector actually trades. This is one of the largest small-business M&A pools in the country. The mainstream paths: buy or operate an SBA-financeable local business (a staffing branch, a cleaning or landscaping route, a pest or security firm, a co-packer, a call-answering service, a collection agency), or back a PE roll-up in a chosen niche. Prize recurring revenue, low churn, route/branch density, documented compliance and licensing, low owner-dependence, and AI wrapped around the workflow rather than competing with it on price. Diligence centers on verified net cash flow, contract and customer concentration, utilization/attrition/fill rates, insurance and licensing records, working capital, leverage, and a credible answer to whether AI is the target's tailwind or its obituary.

Outlook (forward-looking judgment; the federal data contain no growth forecast). Do not underwrite 561 as one number — it splits into stories running in different directions. The data, annuity, and franchise core (credit bureaus, alarm monitoring, pest and route services, PEOs, dominant trade shows and ticketing, and facilities support riding the data-center build-out) looks durable and even favored — insulated from or helped by AI, protected by switching friction, moats, or compliance barriers. The commodity-labor core (call centers, document prep, low-skill placement and light-industrial temp, routine admin, and undifferentiated guarding sold by the plain billed hour) faces a structural, AI-driven squeeze, where winners reposition around complex, regulated, human-in-the-loop work and losers sell an undifferentiated hour. Across the whole subsector, value is created less by the market expanding than by operators improving mix and consolidators rolling up small units and data networks — the durable tailwind is outsourcing, the durable headwind is labor and technology. Public investors get concentrated quality in a few corners and contrarian optionality in others; private investors get a vast, heterogeneous, cash-generative roll-up field — provided they underwrite each child and niche on its own economics and treat the three-digit code as a filing convenience, not a market. For the full, industry-by-industry analysis — company rosters, unit economics, regulation, and diligence checklists — read the eight child primers: 5611, 5612, 5613, 5614, 5615, 5616, 5617, and 5619.

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Sources

This rollup synthesizes our ground-truth federal statistics for NAICS 561 and the eight already-written child primers, each of which carries its own complete numbered Sources list (Census, SEC filings, and sector-specific regulators and trade bodies).

1. Histometrics ground-truth federal file — NAICS 561, Administrative and Support Services: U.S. Census Bureau, 2022 Economic Census — Concentration of Largest Firms (receipts $1,209,248,536K; firms 359,824; CR4 7.8% / CR8 10.9% / CR20 17.4% / CR50 25.6%; HHI 25.1) and 2023 County Business Patterns (establishments 421,777; employees 12,960,998; annual payroll $727,355,099K; Q1 payroll $182,379,194K). No nonemployer counts or per-firm operating metrics supplied at this level. https://www.census.gov/programs-surveys/economic-census.html; https://www.census.gov/programs-surveys/cbp.html
2. Histometrics child primer — NAICS 5611 Office Administrative Services (receipts ~$90.8B; 550,384 employees; CR4 3.4%, HHI 7.4; MSO/fund-admin PE roll-up; AI swing factor). primer-5611-DRAFT.md
3. Histometrics child primer — NAICS 5612 Facilities Support Services (receipts $41.2B; 283,836 employees; CR4 22.3%, HHI 211.6; ABM/EMCOR/Aramark, GEO/CoreCivic, V2X/KBR/Amentum; data-center tailwind). primer-5612-DRAFT.md
4. Histometrics child primer — NAICS 5613 Employment Services (receipts $557.87B; 7,790,831 employees; CR4 17.0%, HHI 105.4; staffing/search/PEO; gross-vs-net caveat; TriNet/Insperity/ADP/Paychex). primer-5613-DRAFT.md
5. Histometrics child primer — NAICS 5614 Business Support Services (receipts ~$84.10B; 673,396 employees; CR4 13.9%, HHI 82.2; call centers/collections/credit bureaus/document prep; Equifax/TransUnion/FICO/Experian). primer-5614-DRAFT.md
6. Histometrics child primer — NAICS 5615 Travel Arrangement and Reservation Services (receipts $69.017B; 186,812 employees; CR4 34.2%, HHI 396.4; OTAs, GDS, ticketing, CVBs). primer-5615-DRAFT.md
7. Histometrics child primer — NAICS 5616 Investigation and Security Services (receipts $80.74B; 1,011,407 employees; CR4 25.6%, HHI 215.5; guards/cash/screening vs. monitoring RMR; ADT/Alarm.com/Brink's/First Advantage). primer-5616-DRAFT.md
8. Histometrics child primer — NAICS 5617 Services to Buildings and Dwellings (receipts $226.0B; 2,156,568 employees; CR4 6.4%, HHI 17.2; janitorial/landscaping/pest; Rollins/Rentokil/BrightView; ~90 PE landscaping platforms; ~434,554 landscaping nonemployers). primer-5617-DRAFT.md
9. Histometrics child primer — NAICS 5619 Other Support Services (receipts ~$59.50B; 307,764 employees; CR4 7.6%, HHI 29.8; co-packing/trade shows/route services; Sonoco/Iron Mountain/WM/RB Global; Apollo–Emerald). primer-5619-DRAFT.md
10. U.S. Census Bureau — 2022 NAICS Manual: Subsector 561 Administrative and Support Services and its industry groups 5611–5619 (definitions, structure, and scope exclusions incl. in-house/captive operations and waste-management subsector 562). https://www.census.gov/naics/