Regional Codes ...
For statistical purposes, the US Census Bureau has divided the country into four Regions. Gillis is located in Region #4 (the West Region).
In turn, the US Census Bureau has further divided each Region into Divisions. Gillis is located in Division #9 (the Pacific Division).
The Office of Management and Budget (OMB) has created ten Federal Regions. Gillis is located in Region IX (Region 9).
The Federal Emergency Management Agency (FEMA) has created ten Management Regions. Gillis is located in Region IX (Region 9).
Referenced FIPS Records ...
FIPS Code: 06/29485 (Place Name: Gillis)
County: Siskiyou (FIPS State/County: 06/093)
Identifies a populated place (ie- Gillis) that is wholly or substantially located outside the boundaries of any incorporated place or CDP (Census Designated Place) that has an authoritative common name recognized by the U.S. Geological Survey (USGS).