Historical population
| Census | Pop. | Note | %± |
| 2010 | 6,149 | | — |
|---|
| 2020 | 6,919 | | 12.5% |
|---|
Franklin first appeared as a census designated place in the 2010 U.S. census.[20]
The 2020 United States census reported that Franklin had a population of 6,919. The population density was 3,416.8 inhabitants per square mile (1,319.2/km2). The racial makeup of Franklin was 30.7% White, 2.9% African American, 2.4% Native American, 16.6% Asian, 0.1% Pacific Islander, 29.6% from other races, and 17.7% from two or more races. Hispanic or Latino of any race were 60.0% of the population.[21]
The whole population lived in households. There were 1,875 households, out of which 48.9% included children under the age of 18, 51.0% were married-couple households, 8.8% were cohabiting couple households, 24.6% had a female householder with no partner present, and 15.6% had a male householder with no partner present. 15.6% of households were one person, and 7.0% were one person aged 65 or older. The average household size was 3.69.[21] There were 1,500 families (80.0% of all households).[22]
The age distribution was 31.9% under the age of 18, 10.9% aged 18 to 24, 26.1% aged 25 to 44, 22.1% aged 45 to 64, and 9.1% who were 65 years of age or older. The median age was 30.1 years. For every 100 females, there were 98.8 males.[21]
There were 1,980 housing units at an average density of 977.8 units per square mile (377.5 units/km2), of which 1,875 (94.7%) were occupied. Of these, 64.4% were owner-occupied, and 35.6% were occupied by renters.[21]
In 2023, the US Census Bureau estimated that 19.2% of the population were foreign-born. Of all people aged 5 or older, 51.2% spoke only English at home, 40.9% spoke Spanish, 7.7% spoke other Indo-European languages, and 0.2% spoke Asian or Pacific Islander languages. Of those aged 25 or older, 76.1% were high school graduates and 23.5% had a bachelor's degree.[23]
The median household income was $61,071, and the per capita income was $29,141. About 22.0% of families and 23.4% of the population were below the poverty line.[24]
In the United States House of Representatives, Franklin is in California's 13th congressional district, represented by Democrat Adam Gray as of January 2025.