Louisville is a city located in Boulder County, Colorado. As of the 2000 census, the city has a total population of 18,937.
In July of 2005, CNN/Money and Money magazine ranked Louisville fifth on its list of the 100 best places to live in the United States.
Louisville is located at 39°58'34"N, 105°8'39"W (39.976035, 105.144067).
According to the United States Census Bureau, the city has a total area of 22.2 km2 (8.6 mi2). 22.1 km2 (8.5 mi2) of it is land and 0.1 km2 (0.04 mi2) of it is water. The total area is 0.47% water.
As of the census of 2000, there are 18,937 people, 7,216 households, and 4,950 families residing in the city. The population density is 858.2/km2 (2,223.6/mi2). There are 7,389 housing units at an average density of 334.8/km2 (867.6/mi2). The racial makeup of the city is 91.17% White, 0.93% African American, 0.54% Native American, 3.55% Asian, 0.08% Pacific Islander, 1.83% from other races, and 1.90% from two or more races. 5.02% of the population are Hispanic or Latino of any race.
There are 7,216 households out of which 40.5% have children under the age of 18 living with them, 56.3% are married couples living together, 8.6% have a female householder with no husband present, and 31.4% are non-families. 22.4% of all households are made up of individuals and 4.6% have someone living alone who is 65 years of age or older. The average household size is 2.61 and the average family size is 3.13.
In the city the population is spread out with 28.7% under the age of 18, 6.3% from 18 to 24, 35.6% from 25 to 44, 23.3% from 45 to 64, and 6.1% who are 65 years of age or older. The median age is 36 years. For every 100 females there are 98.6 males. For every 100 females age 18 and over, there are 95.0 males.
The median income for a household in the city is $69,945, and the median income for a family is $81,512. Males have a median income of $57,159 versus $36,659 for females. The per capita income for the city is $31,828. 3.0% of the population and 2.1% of families are below the poverty line. Out of the total population, 2.2% of those under the age of 18 and 5.6% of those 65 and older are living below the poverty line.