NOTICE: GNIS Changes Unique IDs for Cities

March 26, 2008

The Issue

In January of 2006 the Geographic Names Information System (GNIS) feature IDs became the official federal codes for identifying cities and townships across the nation. The FIPS 55 place codes, that had been the official codes, were retired at that time, although they will continue to be maintained up until the 2010 census.

Initially the GNIS contained two records for every city, each having a different 'feature type' within GNIS. One was a 'populated place' feature and the other was a 'civil' feature. Each had its own unique ID. Townships, however, had only a 'civil' feature type record. At that time the GNIS database matched the FIPS codes for cities to the 'populated place' feature. FIPS codes for townships were match to the 'civil' township features. As a result, and as directed by the GNIS administrators, the Metropolitan Council's city and township lookup table used the 'populated place' feature ID for cities as the official GNIS unique ID.

In early 2008 a change was made in GNIS to match the FIPS place codes to the 'civil' feature for each city instead of the 'populated place' feature. In the long run, this makes much more sense, making both cities and townships 'civil' features within GNIS. However, this means that the official GNIS unique ID for every city in Minnesota has changed as of March 2008.

What Does This Affect?

This change will affect several Metropolitan Council and MetroGIS datasets. A city and township lookup table will contain both old and new codes to help with the transition.

As of April 1, 2008 (no joke involved... really), three datasets published by the Metropolitan Council on DataFinder.org will contain the new GNIS IDs for cities. Two other datasets and the MetroGIS TLG Street Centerline dataset also contain the GNIS IDs. It may take longer for these datasets to convert to the new codes. A list of known affected datasets is shown below.

Datasets to be Updated April 1

County CTU Lookup Table

  • county_ctu_lut.dbf & county_ctu_lut.xls (metadata)
  • This is a master city and township code cross reference table for the seven metro counties. Within this database, the GNIS unique IDs will be updated in three relevant fields: CTU_ID, COCTU_ID and CTU_ID_CEN.

Cities and Townships Shapefiles

  • ctu.shp (metadata)
  • Within this shapefile, the GNIS unique IDs will be updated in the CTU_ID field.

Counties Cities and Townships Combined Shapefile

  • county_ctu.shp (metadata)
  • Within this shapefile, the GNIS unique IDs will be updated in the CTU_ID and COCTU_ID and CTU_ID_CEN fields.

Datasets to be Updated After April 1

Value of Non-Residential Construction Added in 2006

  • nonres_2006.shp (metadata)
  • This dataset contains the CTU_ID field.

Regional Planned Land Use - Twin Cities Metropolitan Area

  • landuse_planned.shp (metadata)
  • This dataset contains the CTU_ID field.

TLG Street Centerlines

  • tlg_roads.shp (metadata)
  • This dataset contains these GNIS IDs in the GNIS_L and GNIS_R fields.

For more information, see the metadata for each dataset (links above), including contact person.