Regional Codes ...
For statistical purposes, the US Census Bureau has divided the country into four Regions. Island Mountain is located in Region #4 (the West Region).
In turn, the US Census Bureau has further divided each Region into Divisions. Island Mountain is located in Division #9 (the Pacific Division).
The Office of Management and Budget (OMB) has created ten Federal Regions. Island Mountain is located in Region IX (Region 9).
Referenced GNIS Records ...
GNIS ID #1658842 (Name of Record: Island Mountain)
Class: populated place
A place or area having clustered or scattered buildings and a permanent population (such as a city, settlement, town or village). The boundaries may or may not coincide with the perceived population.
A 'populated place' record may have a corresponding 'census' or 'civil' record. The information contained in the 'populated place' record applies only to the class and should not be confused with either the 'census' and 'civil' classes.
Map Name: Lake Mountain
Lat: 40.0262607 Lon: -123.4903007
Referenced FIPS Records ...
FIPS Code: 06/36854 (Place Name: Island Mountain)
County: Trinity (FIPS State/County: 06/105)
Identifies a populated place (ie- Island Mountain) 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).