Field consultants and firms by state

By Ben Hinton. Updated .

This study counts the cultural resource, environmental, stormwater and forestry consultants listed in public directories, state by state. It uses 19 sources: state historic preservation office consultant rosters, three credential registries and four state consulting-forester directories.

Agencies can use it to see where qualified consultants are listed. Firms can use it to size a market or check how crowded a state roster is. People looking for work can see where credential holders are concentrated. Every number is an aggregate count. No names or contact details are published.

Findings

  1. The 19 directories in this study hold 11,120 listings. After removing 149 cross-listings, that is 10,971 unique people and firms. 10,912 of the listings are in a US state or DC.
  2. California has 740 of the 4,485 Registered Professional Archaeologists who list a US state (16.5%), more than Texas (301) and Florida (267) combined.
  3. California accounts for 1,559 of the 5,059 EnviroCert credential holders with a US address (30.8%). Ohio is second with 422.
  4. CPESC is the most widely held EnviroCert credential: 2,677 of the 5,064 US holders have it, against 2,155 with CESSWI and 526 with CPSWQ.
  5. Of the 942 listings on 12 state historic preservation office consultant rosters, 371 (39.4%) give an address in a different state from the office that lists them. On South Carolina's roster it is 61 of 78.
  6. The ABCEP directory lists 220 Certified Environmental Professionals. 186 show a US address, and Florida has the most (31).

These are counts of directory listings, not of everyone working in the field. See the methodology below before comparing states.

Listings by state

All 50 states and DC, sorted by total listings. Select a column header to sort by it. “Unique” removes people and firms who appear in more than one directory in that state.

Listed field consultants and firms by US state. Select a column header to sort.
California2,3202,3191,55974050160
Texas64564531730183190
Ohio*631605422881164850
Pennsylvania46646327514221101513
Indiana40938729957481723
New York40039721716216950
Florida3603595326793310
Illinois*†347328150855024359
North Carolina345342181139161190
Washington†31931956150736100
Georgia307306121167151040
Colorado2752751041632060
New Mexico*263254261081286310
Arizona2612615619500100
Virginia243242671614383
Tennessee221219141724240
Oregon197197431531000
Michigan*18417219571031341
Maryland†170170487533638
Kentucky*1681563755755110
Alabama159159100563300
Idaho*1461362138864110
Massachusetts14014077536440
Louisiana13613653773130
Alaska*125122844702430
Minnesota119116445615340
Nevada11911933851100
Missouri112107465312901
Wisconsin108105385117502
South Carolina*1051043057171210
New Jersey10210229683120
New Hampshire939266216400
Utah858518632220
Oklahoma757419551100
Maine7270431712800
Hawaii666631340010
Vermont*65613110241900
West Virginia616134185404
Connecticut606035232200
Arkansas585811460010
Rhode Island484882712610
Iowa474622174222
Montana†464652133314
District of Columbia434315280000
Wyoming35356290000
Kansas323214162000
Nebraska323211191010
Mississippi31319220000
South Dakota24243164210
North Dakota22223180010
Delaware15155100000

* Only Alaska, Idaho, Illinois, Kentucky, Michigan, New Mexico, Ohio, South Carolina and Vermont have a SHPO roster in the data. A state marked * has its own roster here. Roster listings in other states are consultants based there who appear on one of those rosters, so a zero means no data, not no consultants.

† Only Illinois, Maryland, Montana and Washington have a consulting-forester directory in the data.

RPA counts are the directory's own per-state totals as of October 31, 2026. Other listings were read on August 13, 2026.

Who is on each SHPO roster

State historic preservation offices publish lists of consultants who meet the Secretary of the Interior's professional qualification standards. Many listed firms are based in another state.

SHPO consultant rosters by where listed consultants are based
RosterListingsBased in that stateBased in another state
Alaska67670
Idaho928111
Illinois632934
Kentucky645212
Michigan24791156
New Mexico (2 lists)1311283
Ohio (2 lists)1248242
South Carolina781761
Vermont (2 lists)762452

Methodology

What is counted. Listings in public directories that exist so people can find a qualified consultant. EnviroCert, RPA and ABCEP list individual credential holders. SHPO rosters and forester directories list firms and sole practitioners who asked to be included. People and firms are counted in the state of their listed address, which is often not the state whose roster lists them.

What it is not. A census. Many working archaeologists hold no RPA registration, many stormwater inspectors hold a state credential instead of an EnviroCert one, and most states have no SHPO roster in this data. Differences between states in the roster and forester columns mostly reflect which rosters exist, not where consultants work. Compare states within a single column, preferably EnviroCert or RPA, which cover the whole country.

Duplicates. Listings are linked into one person or firm when they share an email address; or, across different sources only, when the normalized person name (first and last word, lowercased, accents, middle initials and credentials removed) and state match; or, for roster entries with a firm name but no person, when the normalized firm name (legal suffixes removed) and state match. Same-name rows within one registry are not merged, because those registries already separate people by name, city and state. RPA registrants without a row in our copy cannot be matched and count as unique, so unique counts are an upper bound. Across all sources, 149 of 11,120 listings were merged this way.

Firms and individuals. The named-firm column counts distinct firm names on SHPO roster entries. Names were parsed from PDF text, and 526 of 852 roster entries have a parsed firm name, so the column undercounts.

Excluded sources. The Association of Consulting Foresters directory was not used, because its use policy forbids building lists from it. Both Wisconsin Historical Society rosters were left out, because the Society's site terms restrict republishing its content for commercial purposes without written permission. We checked the published terms of every other source, and none restricts publishing counts derived from it.

Sources used

Download the data

Counts of listed cultural resource, environmental, stormwater and forestry consultants and firms in each US state and DC, by credential and source: 11,120 listings (10,971 unique) from 19 public directories. Aggregate counts only. The JSON download adds per-source totals, terms notes, SHPO roster summaries and EnviroCert credential counts.

CSVJSON
Last updated
Methodology
Counts come from 19 public directories: the EnviroCert International certification registry (stormwater and erosion control credentials), the Register of Professional Archaeologists directory, the ABCEP directory of Certified Environmental Professionals, 12 state historic preservation office (SHPO) consultant rosters covering Alaska, Idaho, Illinois, Kentucky, Michigan, New Mexico, Ohio, South Carolina and Vermont, and 4 consulting-forester directories covering Illinois, Maryland, Montana and Washington. Listings were read on 2026-08-13. RPA state counts are the directory's own published per-state totals, read on 2026-10-31. People and firms are counted in the state of their listed address, not the state whose roster lists them. These are directory listings, not a census of the profession. Each directory lists only people who hold that credential or asked to be listed. States with a SHPO roster or forester directory in the data show higher counts in those columns because of coverage, not because more consultants work there. Most states have no roster in the data, so a zero in a roster column means no data, not no consultants. Deduplication: Listings are linked into one person or firm when they share an email address; or, across different sources only, when the normalized person name (first and last word, lowercased, accents, middle initials and credentials removed) and state match; or, for roster entries with a firm name but no person, when the normalized firm name (legal suffixes removed) and state match. Same-name rows within one registry are not merged, because those registries already separate people by name, city and state. RPA registrants without a row in our copy cannot be matched and count as unique, so unique counts are an upper bound. Excluded: the Association of Consulting Foresters directory, whose use policy forbids building lists from it, and both Wisconsin Historical Society rosters, because the Society's site terms restrict republishing its content for commercial purposes without written permission. Every other source's terms were checked and none restricts publishing counts. Individuals and firms: EnviroCert, RPA and ABCEP list individuals. SHPO rosters and forester directories mix firms and sole practitioners; the named-firm column counts distinct firm names parsed from SHPO roster entries. It undercounts, because names were parsed from PDF text: 526 of 852 roster entries have a parsed firm name and 287 have no parsed name at all.
Sources

Counts derived from public directories published by EnviroCert International, the Register of Professional Archaeologists, the Academy of Board Certified Environmental Professionals, and the state historic preservation and forestry offices listed under sources.

License
Compiled by FieldTap and published under CC BY 4.0. You can reuse it, including commercially, if you credit “FieldTap (fieldtap.app)” and the original source. The license covers FieldTap's counts and compilation. No names, contact details or other individual listings from the underlying directories are included.

FieldTap is field data collection software for these crews. Start free trial