Smithsonian trinomial


Smithsonian trinomials are unique identifiers assigned to archaeological sites in many states in the United States. They are composed of one or two digits coding for the state, typically two letters coding for the county or county-equivalent within the state, and one or more sequential digits representing the order in which the site was listed in that county. The Smithsonian Institution developed the site number system in the 1930s and 1940s. The 48 states then in the union were assigned numbers in alphabetical order. Alaska was assigned number 49 and Hawaii was assigned number 50 after those states were admitted to the union. There are no Smithsonian trinomial numbers assigned for the District of Columbia or any United States territories.
Most states use trinomials of the form "nnAAnnnn", but some specify a space or dash between parts of the identifier, i.e., "nn AA nnnn" or "nn-AA-nnnn". Some states use variations of the trinomial system. Arizona, California, Connecticut, Maine, Rhode Island and Vermont use two-letter abbreviations of the state name instead of the Smithsonian number. Alaska uses three-letter abbreviations for USGS map quadrangles in place of the county code. Arizona uses a five-part identifier based on USGS maps, specifying quadrangles, then rectangles within a quadrangle, a sequential number within the rectangle, and a code identifying the agency issuing the sequential number. California uses a three-letter abbreviation for counties. Connecticut and Rhode Island do not use any sub-state codes, with site identifiers consisting of the state abbreviation and a sequential number series for the whole state. Delaware uses a single letter code for counties and adds a block code within each county, with sequential numbers for each block. Hawaii uses a four-part identifier, "50" for the state, a two-digit code for the island, then a two-digit code to designate the USGS topographical quad, plus a four digit sequential site number for sites on each island.

Archaeological site identification codes used by states

StateFormatCounty or equivalent codes
Alabama1AAnnnnAA:
Alaska49‑AAA‑nnnnAAA:
ArizonaAZ AA:nn:nnAA:nn:
Arkansas3AAnnnnList of counties in Arkansas
CaliforniaCA‑AAA‑nnnnAAA:
Colorado5AAnnnnList of counties in Colorado
ConnecticutCT‑nnnnnNo county code; state abbreviation and a sequential number only
Delaware7ABnnnnA: K = Kent County, N = New Castle County, and S = Sussex County. B:
Florida8AAnnnnList of counties in Florida
Georgia9AAnnnnAA:
Hawaii50‑nn‑nn‑nnnnnn: 10 = Hawaii, 20 = Kaho'olawi, 30 = Kaua'i, 40 = Lana'i, 50 = Maui, 60 = Moloka'i, 80 = O'ahu, 91 = Necker, 92 = Nihoa
Idaho10AAnnnn
Illinois11AAnnnnList of counties in Illinois
Indiana12AAnnnnList of counties in Indiana
Iowa13AAnnnnAA:
Kansas14AAnnnnAA:
Kentucky15AAnnnnList of counties in Kentucky
Louisiana16AAnnnnList of parishes in Louisiana
MaineME-nn-nn
Maryland18AAnnnnList of counties in Maryland
Massachusetts19-AA-nnnn
Michigan20AAnnnnList of counties in Michigan
Minnesota21AAnnnnAA:
Mississippi22‑AA‑nnnnList of counties in Mississippi
Missouri23AAnnnnList of counties in Missouri
Montana24AAnnnn
Nebraska25AAnnnn
Nevada26AAnnnn
New Hampshire27‑AA‑nnnnAA: Belknap Carroll Cheshire Coos Grafton Hillsborough Merrimack Rockingham Strafford Sullivan
New Jersey28AAnnnn
New Mexico29AAnnnn
North Carolina31AAnnnnAA: Alamance Alexander Alleghany Anson Ashe Avery Beaufort Bertie Bladen Brunswick Buncombe Burke Cabarrus Caldwell Camden Carteret Caswell Catawba Chatham Cherokee Chowan Clay Cleveland Columbus Craven Cumberland Currituck Dare Davidson Davie Duplin Durham Edgecombe Forsyth Franklin Gaston Gates Graham Granville Greene Guilford Halifax Harnett Haywood Henderson Hertford Hoke Hyde Iredell Jackson Johnston Jones Lee Lenoir Lincoln Macon Madison Martin McDowell Mecklenburg Mitchell Montgomery Moore Nash New Hanover Northampton Onslow Orange Pamlico Pasquotank Pender Perquimans Person Pitt Polk Randolph Richmond Robeson Rockingham Rowan Rutherford Sampson Scotland Stanly Stokes Surry Swain Transylvania Tyrrell Union Vance Wake Warren Washington Watauga Wayne Wilkes Wilson Yadkin Yancey
North Dakota32AAnnnnAA:
Ohio33‑AA‑nnnnAA:
Oregon35‑AA‑nnnnList of counties in Oregon
Pennsylvania36‑AA‑nnnnList of counties in Pennsylvania
Rhode IslandRI‑nnnnNo county code; state abbreviation and a sequential number only
South Carolina38‑AA‑nnnnList of counties in South Carolina
South Dakota39AAnnnn
Tennessee40AAnnnnAA:
Texas41‑AA‑nnnnAA:
Utah42‑AA‑nnnnList of counties in Utah
VermontVT‑AA‑nnnnAA: Addison Bennington Caledonia Chittenden Essex Franklin Grand Isle Lamoille Orange Orleans Rutland Washington Windham Windsor
Virginia44-AA-nnnn
Washington45‑AA‑nnnnList of counties in Washington
West Virginia46‑AA‑nnnnList of counties in West Virginia
Wisconsin47‑AA‑nnnnList of counties in Wisconsin
Wyoming48AAnnnnList of counties in Wyoming and also YE for sites within Yellowstone National Park