As of the special census of 2007, there were 26,211 people, 9,900 households, and 5,979 families residing in the village. The population density was 5,014.4 people per square mile (1,934.8/km²). There were 10,269 housing units at an average density of 2,097.1/sq mi (809.2/km²). The racial makeup of the village was 78.02% White, 5.38% African American, 0.13% Native American, 11.95% Asian, 2.41% from other races, and 2.11% from two or more races. Hispanic or Latino people of any race comprised 6.98% of the population.
There were 9,900 households; 29.1% of these households had children under the age of 18 living with them. 47.1% were married couples living together, 10.4% had a female householder with no husband present, and 39.6% were non-families. 32.5% of all households were made up of individuals and 11.8% had someone living alone who was 65 years of age or older. The average household size was 2.37 and the average family size was 3.05.
The population was spread out with 21.9% under the age of 18, 8.3% from 18 to 24, 33.8% from 25 to 44, 20.3% from 45 to 64, and 15.7% who were 65 years of age or older. The median age was 36 years. For every 100 females there were 87.4 males. For every 100 females age 18 and over, there were 82.9 males.
The median income for a household in the village was $51,422, and the median income for a family was $64,472. Males had a median income of $42,909 versus $33,690 for females. The per capita income for the village was $26,394. About 3.8% of families and 5.8% of the population were below the poverty line, including 4.8% of those under age 18 and 8.5% of those age 65 or over.
Westmont has a station on Metra's BNSF Railway Line, which provides daily rail service between Aurora, Illinois and Chicago, Illinois (at Union Station). The East-West Tollway, located north of the Village, Interstate 55 to the South, Interstate 294 to the East and Interstate 355 to the West, provide access to the rest of the Chicago Region.