Geocodes are identifiers assigned to a predefined geographic areas by either standards organizations such as ANSI or governments.  For example the US government uses Federal Information Processing Standards (FIPS) where the first 2 digits are the state identifier and the next 3 digits is the county.  If the area is the entire state, the county field is "000".  For example, the entire state of Massachusetts is "33000".  ANSI has replaced many of the FIPS standards, but the US government Integrated Public Alert and Warning System (IPAWS) uses both the FIPS and ANSI standards depending on the reporting party (e.g. one state may use FIPS and another use both in their alerts). 

For the Limelight XE implementation of IPAWS, use the 5 digit FIPS code (previously known as FIPS-55) which is in the format: 2 digit state + 3 digit county.  For example, "48009" is Archer County in TX. Below is a list for convenience in setting up the IPAWS filter to only show alerts for certain states or counties reducing the flood of alerts that occur daily nationwide. Click the state name to expand the list to the county level.

United States FIPS Codes