According to the United States Census Bureau, the city has a total area of 7.4 square miles (19.3 km²), all of it land.
There were 3,251 households out of which 31.1% had children under the age of 18 living with them, 48.1% were married couples living together, 14.8% had a female householder with no husband present, and 33.1% were non-families. 29.5% of all households were made up of individuals and 13.7% had someone living alone who was 65 years of age or older. The average household size was 2.39 and the average family size was 2.94.
In the city the population was spread out with 25.2% under the age of 18, 9.1% from 18 to 24, 28.5% from 25 to 44, 21.8% from 45 to 64, and 15.4% who were 65 years of age or older. The median age was 36 years. For every 100 females there were 89.9 males. For every 100 females age 18 and over, there were 85.7 males.
The median income for a household in the city was $32,001, and the median income for a family was $38,807. Males had a median income of $30,955 versus $21,783 for females. The per capita income for the city was $16,467. About 10.9% of families and 13.7% of the population were below the poverty line, including 15.9% of those under age 18 and 18.1% of those age 65 or over.
Both Major Leauge Baseball pitcher Joe Blanton and actress Annie Potts were born in Nashville, Tennessee but raised in Franklin.
PGA golfer Kenny Perry resides in Franklin.
University of Kentucky football offensive coordinator and head coach-in-waiting Joker Phillips was born and raised in Franklin. Phillips also attended and played at UK.
Singers Johnny Cash and June Carter were married in a private ceremony at Franklin United Methodist Church on March 1, 1968. Longtime friend Merle Kilgore was best man.
Kentucky Downs, formerly known as Dueling Grounds Racetrack, (owned by Churchill Downs, Turfway Park, and Kelly Racing Farms), is located right on the Kentucky–Tennessee border in Franklin. Kentucky Downs hosts the Kentucky Cup Turf Festival, a full card of world class racing featuring four major turf stakes. Kentucky Downs also hosts year-round simulcasts for the Kentucky-Tennessee market.