During the American Civil War on September 1, 1862, the Battle of Chantilly was fought here. Following his victory at the Second Battle of Bull Run (or Second Manassas), Confederate General Robert E. Lee directed Major General Thomas J. "Stonewall" Jackson to cross Bull Run on August 31 and sweep around the position of Major General John Pope's Union Army of Virginia at Centreville. Reaching the Little River Turnpike northwest of Centreville, Jackson turned southeastward toward Fairfax Court House (now Fairfax, Virginia) to strike in rear of Pope's army.
During September 1, Pope, apprised of Jackson's movement, began to withdraw toward Fairfax Court House. Late in the day, Jackson clashed with Union forces under Brigadier General Isaac Stevens and Major General Philip Kearney near Ox Hill, west of Fairfax. During the ensuing battle, which was fought amid a raging storm, both Union generals Stevens and Kearney were killed. The fighting ended at dusk, and Pope's army continued its withdrawal to Fairfax and subsequently to the Washington defenses.
Although commercial and residential development now covers most of the Chantilly (Ox Hill) battlefield, a small county park preserves a two-acre portion of the battle site.
Chantilly is located at 38°52'30" North, 77°24'9" West (38.874972, -77.402622)1.
As of the census of 2000, there are 41,041 people, 14,840 households, and 10,521 families residing in the town. The population density is 1,359.0/km² (3,519.4/mi²). There are 15,173 housing units at an average density of 502.4/km² (1,301.1/mi²). The racial makeup of the town is 73.34% White, 4.99% African American, 0.29% Native American, 16.36% Asian, 0.06% Pacific Islander, 2.01% from other races, and 2.96% from two or more races. 6.87% of the population are Hispanic or Latino of any race.
There are 14,840 households out of which 38.1% have children under the age of 18 living with them, 60.6% are married couples living together, 7.4% have a female householder with no husband present, and 29.1% are non-families. 20.2% of all households are made up of individuals and 2.1% have someone living alone who is 65 years of age or older. The average household size is 2.75 and the average family size is 3.24.
In the town the population is spread out with 26.1% under the age of 18, 7.8% from 18 to 24, 38.4% from 25 to 44, 23.0% from 45 to 64, and 4.8% who are 65 years of age or older. The median age is 34 years. For every 100 females there are 98.4 males. For every 100 females age 18 and over, there are 96.1 males.
The median income for a household in the town is $87,991, and the median income for a family is $98,202. Males have a median income of $61,954 versus $41,608 for females. The per capita income for the town is $36,200. 2.3% of the population and 1.3% of families are below the poverty line. Out of the total people living in poverty, 1.7% are under the age of 18 and 5.5% are 65 or older.