DATABASE NAME

     CNTY_POL:  1:100,000 base map scale County Political
     Boundaries

DATABASE DESCRIPTION

     1:100,000 base map scale political county boundaries for the
     United States.

ORIGINATING AGENCY

     Bureau of Transportation Statistics

AGENCY RESPONSIBLE FOR MAINTAINING DATA

     Bureau of Transportation Statistics

CONTACT

     National Transportation Atlas Databases
     Bureau of Transportation Statistics
     U.S. Department of Transportation
     Washington, DC  20590
     (202) 366-DATA
     Internet:  info@bts.gov

SOURCE

     1990 1:100,000 Census TIGER/Line records supplemented by
     editing performed by Oak Ridge National Laboratory

ACCURACY

     80 m (260 ft) root-mean square positional accuracy

TYPE OF GIS DATABASE

     Line database with links

FILES/SIZE/NUMBER OF RECORDS

     One ASCII file

     1)   cnty_pol.lin   link file contains link attributes,
                         locations, and shapes

     Approximate size of file:     9,545,000 bytes
     Approximate number of links:  9600

FILE STRUCTURE

     The file is ASCII-space delimited.

     The Link File

   FIELD  ITEM                TYPE      REMARKS

     1    Record ID           Num       Unique record number
     2    Boundary Code       Num       Code identifying type of
                                        boundary
                                        1    International
                                             boundary
                                        3    Ocean
                                        5    State boundary
                                        9    County boundary
     3    FIPS left           Num       County FIPS code on left
                                        side of link
     4    FIPS right          Num       County FIPS code on right
                                        side of link
     5    N                   Num       Number of following
                                        Longitude-Latitude pairs
                                        in decimal degrees
     6    Longitude           Float     Implied decimal} First
     7    Latitude            Float     6 places      }  pair

          Long-Lat pairs      Float     Shape points of the link
          repeat N-2 times    Float     in pairs of long-lat

          Longitude           Float     Implied decimal}  Final
          Latitude            Float     6 places      }  pair 

DISCUSSION

     No additional discussion.