Site Numbers in Archaeology

The first step in my Campus Archaeology project this year is getting site numbers. These numbers are based on the state, county and site number. They are designated by the Office of the State Archaeologist, and are unique to each site. The reason that you want your site identified with a site number is that it makes organization of materials easier since everything from the site will be associated with a single ID, it makes it easier to find in the state records and it becomes officially part of the state’s archaeological records (which is important as we move to the next stage of accessioning).

What a site number means, via Crow Canyon Archaeology
What a site number means, via Crow Canyon Archaeology

The numbers are known as the Smithsonian Trinomial. They were created in order to give every archaeological site in the US a unique identifier. They were first employed beginning in the 1930s and 1940s. The numbers were developed during two major projects that spanned multiple states and necessitated a US wide system of archaeological site designation: developed first in the 1930s Works Progress Administration fieldwork and perfected during the 1940s River Basin Survey (Webster).

The site number is based on three parts. First is the state number. Each state has a unique number that is based on the alphabetical order of all US states and territories from the 1940s. Based on this, Michigan is 20 and other states like Colorado are 5 or Tennessee is 40.  Due to the date of the creation of these numbers, states like Alaska and Hawaii which joined the US later are not in alphabetical order, but are 49 and 50, respectively.

MI County Map, via Wikimedia

The second part is not a number, but consists of two letters that designate the county. Michigan State University is located in Ingham county, so the initials used are ‘IN’. If we were in Saginaw County we would have the initials ‘SA’. Not every state follows this, for example Alaska has a three letter identifier second that  is based on USGS map quadrangles in place of the county code.

Finally is the number of the site which is a sequential digit based on when the number for the site was requested for it. Saints’ Rest is the 169th archaeological site found in Ingham county and therefore is 169. This number is the same throughout the US, though it can mean the number the site was registered in the county or in the USCG map quadrangle.

Here is a little quiz on creating site numbers…

1) Based on what you just learning, what is the complete site number for Saints’ Rest?

  1. 40SA169
  2. 20IN169
  3. 169IN20
  4. 5IN170

2) You found a new archaeological site in Grand Rapids, MI. It is the 356th site that has been found in this county. What would the number be? (Use the county map for reference, Grand Rapids is located in Kent Country to the west)

  1. 20IN356
  2. 356KN20
  3. 20KN356
  4. 20KE356

Bonus: Using the Alaska quad, what would the site number be for the 14th archaeological site found at Howard’s Pass?

  1. 49XHP14
  2. 49XLR14
  3. 49HP14
  4. 50XHP14

If you’d like to learn more about the numbering systems, you can find a listing of the state numbers and how states determine the county number on the Wikipedia page on Smithsonian Trinomials. For more on the history, see this post on site numbers from Chris Webster on DigTech.


1) 2

2) 3

Bonus) 1


Author: Katy Meyers Emery

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