As of the census of 2000, there were 19,680 people, 7,370 households, and 5,498 families residing in the city. The population density was 2,319.8 per square mile (895.7 /km). There were 7,783 housing units at an average density of 917.4 per square mile (354.2 /km). The racial makeup of the city was 93.05% White, 4.38% African American, 0.25% Native American, 0.28% Asian, 0.05% Pacific Islander, 0.59% from other races, and 1.39% from two or more races. Hispanic or Latino of any race were 1.50% of the population.
There were 7,370 households out of which 40.8% had children under the age of 18 living with them, 55.7% were married couples living together, 14.7% had a female householder with no husband present, and 25.4% were non-families. 20.3% of all households were made up of individuals and 7.2% had someone living alone who was 65 years of age or older. The average household size was 2.63 and the average family size was 3.02.
In the city the population was spread out with 28.2% under the age of 18, 10.2% from 18 to 24, 33.9% from 25 to 44, 18.8% from 45 to 64, and 8.9% who were 65 years of age or older. The median age was 31 years. For every 100 females there were 91.6 males. For every 100 females age 18 and over, there were 86.2 males.
The median income for a household in the city was $37,462, and the median income for a family was $42,978. Males had a median income of $31,536 versus $22,275 for females. The per capita income for the city was $17,036. About 9.3% of families and 11.5% of the population were below the poverty line, including 16.1% of those under age 18 and 11.3% of those age 65 or over.
A new 7.4 miles (11.9 km) four-lane divided highway running from a Single-point urban interchange at US 27 north of Nicholasville to US 27 south of Nicholasville is being designed to serve the eastern half of Jessamine County's county seat . The western Nicholasville bypass, signed as US 27, was completed in 1986 with an interchange at KY 29 and a few at-grade intersections.
The eastern bypass of Nicholasville will give commuters another option of bypassing the city, while serving the residents of the eastern half of Jessamine county. In September 2002, the Federal Highway Administration approved an "environmental assessment document" . Right-of-way purchase, estimated at $15 million, is slated to begin in 2006, with relocation of utility lines in 2007 and construction in 2008, and take two years and $73 million to complete.
The Kentucky Transportation Cabinet projects that when the highway opens, that 58,000 will use the western bypass and 45,000 will utilize the eastern bypass .
The Lexington Area MPO is responsible for transportation planning for Fayette and Jessamine Counties. This includes activities such as carpool matching, administering a commuter vanpool program, air quality forecasting, bicycle and pedestrian planning, congestion management, and developing transportation plans and documents.