Geographic features

• Columbia River
• Hanford Nuclear Reservation
• Juniper Dunes Wilderness
• Snake River

Major highways

• SR 260
• Interstate 182
• U.S. 12
• U.S. 395

Adjacent counties

• Adams County - north
• Whitman County - east
• Walla Walla County - southeast
• Columbia County - southeast
• Benton County - southwest
• Grant County - northwest

National protected areas

• Hanford Reach National Monument (part)
• Saddle Mountain National Wildlife Refuge (part)

2020 census

as of the 2020 census, there were 96,749 people in Franklin County.^{[citation needed]}

2010 census

As of the 2010 census, there were 78,163 people, 23,245 households, and 18,163 families residing in the county.^[12] The population density was 62.9 inhabitants per square mile (24.3/km²). There were 24,423 housing units at an average density of 19.7 per square mile (7.6/km²).^[13] The racial makeup of the county was 60.5% white, 1.9% black or African American, 1.8% Asian, 0.7% American Indian, 0.1% Pacific islander, 31.8% from other races, and 3.2% from two or more races. Those of Hispanic or Latino origin made up 51.2% of the population.^[12] In terms of ancestry, 13.1% were German, 6.8% were English, 6.5% were Irish, and 3.3% were American.^[14]

Of the 23,245 households, 49.9% had children under the age of 18 living with them, 57.9% were married couples living together, 13.4% had a female householder with no husband present, 21.9% were non-families, and 16.4% of all households were made up of individuals. The average household size was 3.28 and the average family size was 3.68. The median age was 28.4 years.^[12]

The median income for a household in the county was $47,749 and the median income for a family was $52,218. Males had a median income of $40,604 versus $29,517 for females. The per capita income for the county was $18,660. About 16.5% of families and 19.9% of the population were below the poverty line, including 25.6% of those under age 18 and 13.7% of those age 65 or over.^[15]

The 2019 county population is estimated to be 95,222, a 21.8% increase since 2010. This far outpaces Washington State's overall growth of 13.2% over the same time interval, and puts Franklin County among the fastest-growing counties in the nation.

In 2018 the county contained 28,647 housing units.

Cities

• Connell
• Kahlotus
• Mesa
• Pasco (county seat)

Census-designated places

• Basin City
• West Pasco

Unincorporated communities

• Eltopia
• Harder