The default prefix used for wired telephones in the Hamilton City area is 826.

[4] The large silos of the former Holly Sugar Plant (formerly served by California Northern Railroad) are visible from all over town.

County Road 16) is well known to locals and is 2.1 miles (3.4 km) long.

According to the United States Census Bureau, the CDP has a total area of 0.3 square miles (0.78 km2), all of it land.

[6] The sugar plant closed in 2006, and in 2021 was acquired and renovated by Nutrien Company, a fertilizer producer.

[2] As the town's population grew, to make room for development the local cemetery was moved to a new location about 10 miles north of Artois, California.

There were 539 housing units at an average density of 1,729.1 per square mile (667.6/km2),of which 510 were occupied, 289 (56.7%) by the owners and 221 (43.3%) by renters.

There were 543 housing units at an average density of 1,724.6 per square mile (665.9/km2).

In the state legislature Hamilton City is in the 4th Senate District, represented by Republican Marie Alvarado-Gil,[11] and in the 3rd Assembly District, represented by Republican James Gallagher.

[12] Federally, Hamilton City is in California's 3rd congressional district, represented by Republican Kevin Kiley.

Law enforcement is provided by the Glenn County Sheriff's Department.

Dispatch services for HCFPD are provided by the Tehama-Glenn Unit Headquarters of the California Department of Forestry and Fire Protection in Red Bluff.