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What Gets a Number

The Minnesota State Archaeologist defines an archaeological site as any location containing evidence of past human use that holds potential for archaeological understanding of the past. Just as a site "worthy of preservation" is eligible to be nominated to the National Register of Historic Places, sites "worthy of recordation" (for archaeological purposes) can receive an official site inventory number from the State Archaeologist.

To be worthy of recording, archaeological sites must be at least 50 years old. To get an official site number, a site must have been confirmed by field survey and have a state site form submitted. Archaeological methods must be a principal way we can obtain information about the location.

Bottom Line: Sites are not simply places with evidence of past human use, but places of archaeological interest; an interest that must be shared by multiple archaeologists.

Number Assignment Summary

The following kinds of archaeological sites will be assigned a state site number if an adequate site form is submitted to OSA, the site has been field documented by an archaeologist, and the site is the original location of the recorded activity:

  • All Pre-contact Period sites.
  • All Contact Period sites.
  • Post-contact sites that are 50 years old or of exceptional significance, and contain a recognizable feature or multiple artifacts.
  • Locations of significant archaeological fieldwork.


The following kinds of sites will not be assigned a state site number:

  • Linear sites that can be classed as structures by National Register guidelines (e.g., roads).
  • Constructed properties that can be classed as structures or buildings by the National Register.
  • Active cemeteries.
  • Historic sites less than 50 years old.
  • Finds of animal bone without clearly recognizable human interaction.
  • Traditional Cultural Properties (TCPs) and sacred sites lacking archaeological manifestations.
  • Sites suggested by remote sensing alone.
  • Locations where artifacts probably represent a secondary deposit (e.g., recent fill).


What gets an Alpha Number?

Sites given alpha numbers by the State Archaeologist are locations that probably have or did have archaeological remains, but the presence of these remains has not been confirmed by professional fieldwork.

Alpha sites include:

  • Places documented in historic writings, historic aerial photographs, or historic maps
  • Places containing what appear to be human-made features, but these features have no demonstrated use, cannot be dated to a specific time period, and contain no recognizable artifacts (e.g., pits).
  • Places reported by avocational artifact collectors that haven't been visited by professional archaeologists

What does not receive an official site number?

It is important to distinguish between the characteristics of inventoried archaeological sites and sites in the National Register of Historic Places. The National Register scheme is the basic property type guideline that all federal and state agencies follow and these guidelines help distinguish between what gets a History/Architecture inventory number from the Minnesota Historic Preservation Office (MnHPO) and what gets an archaeological inventory number from the Office of the State Archaeologist (OSA). In short, it is not National Register significance that determines what gets numbered, but archaeological importance.

Historic Sites

The National Register of Historic Places recognizes four basic types of historic properties: Sites, Structures, Buildings, and Objects. A fifth type called Districts represents assemblages of the other four types.

The National Register defines a site as any of the following:

  • A location of a significant event
  • A prehistoric or historic occupation or activity
  • A building or structure, whether standing, ruined, or vanished, where the location itself possesses historic, cultural, or archeological value regardless of the value of any existing structure.


To the National Register a site is an area of land that can contain any type of historic property. It is used when the historic property is more than just the footprint of a human construction (i.e., building, structure), but less than an area containing multiple, discrete properties (i.e., district). It is not reserved exclusively for archaeological properties, but includes cemeteries, gardens, locations of important events (e.g., treaty signings), designed landscapes, and non-designed cultural landscapes. Furthermore, National Register sites are those locations listed in or eligible to the National Register. Thus they must not only exhibit sufficient significance, but also sufficient integrity.

Archaeological Sites

Sites worthy of recording (i.e., eligible to receive an official state site number from the State Archaeologist) do not have to meet the registration requirements for the National Register, but they must not be better classified as a structure, building, or object for the purposes of the National Register.

A site need not have current integrity, only have be a sufficiently documented location of archaeological interest. Even completely destroyed archaeological sites can be given a state site number if sufficient evidence is available documenting where they were once located and what they once contained. Assigned numbers will not be deleted from the OSA archaeological inventory for sites that are destroyed subsequent to their recording. Sites yielding a single prehistoric artifact in what appears to be an original location will be given a number if the artifact can be demonstrated to have archaeological value even if the artifact has been removed. However, sites yielding a single historic period artifact will not be given a number unless the artifact is of exceptional importance (e.g., dating to the Contact Period).

Most linear features such as railroad grades, roads, or ditches will not be given a state site number because they are better described as structures and should be given a History/Architecture inventory number by MnHPO. An exception is portage trails that are over 100 years old, which typically were not constructed, but were paths of least residence to overland travel or the shortest distance between two points. Longer portages typically have discrete loci along the trail (e.g., posses with artifact scatters) that can be given discrete site numbers.

Buildings will not receive site numbers unless they are ruins over 50 years old. Ruins will not receive site numbers if they are part of a farmstead or structural complex where the primary structures still survive (e.g., garage ruin for a residence, barn ruin at a farmstead with a house). Farmsteads and urban house lots will receive numbers if they have surviving in-ground components over 50 years old or significant archaeological work has taken place at the location. Active cemeteries will not receive site numbers.

Animal bone, even the remains of important extinct species such as mammoth or giant bison, will only receive site numbers if they are associated with artifacts or have been altered by humans. Traditional Cultural Properties (TCPs) will not receive site numbers unless they contain artifacts or features that can be examined using archaeological methods. Areas with artifacts moved from their original locations will not receive site numbers unless the artifacts are from an area immediately adjacent to their current location, such as a slumped area.

Features visible on aerial photographs or present on maps will not be given a state site number unless they have been field documented by an archaeologist and a state site form has been completed. Possible sites indicated by remote sensing or soil coring will not be given state site numbers unless archaeological testing has yielded artifacts or physically uncovered features of definite human origin. An exception is for possible burial features (e.g., pits, mound fill) at discrete sites where surface features were previously mapped by Theodore Lewis or other reliable archaeological investigators.

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