As of the 2000 census, the population of the incorporated village was 21,672. The village is an upper middle-class, predominantly white, Roman Catholic and Protestant community. Many families can trace their heritage to Italian and Irish immigrants who moved to Long Island from New York City.
The Garden City name is also applied to unincorporated areas in the region such as Garden City South, Garden City Park and East Garden City. Roosevelt Field, the current shopping center and former airfield from which Charles Lindbergh took off on his landmark 1927 flight, is located in East Garden City.
As of the census of 2006, there were 21,811 people. The population density was 1,567.0/km² (4,059.5/sq mi). There were 7,555 housing units at an average density of 546.3/km² (1,415.2/sq mi). The racial makeup of the village was 94.2% White, 1.2% African American, 0.1% Native American, 3.30% Asian, 0.00% Pacific Islander, 0.4% from other races, and 0.8% from two or more races. Hispanic or Latino of any race were 2.8% of the population.
There were 7,386 households out of which 36.1% had children under the age of 18 living with them, 69.8% were married couples living together, 7.5% had a female householder with no husband present, and 20.7% were non-families. 19.2% of all households were made up of individuals and 12.0% had someone living alone who was 65 years of age or older. The average household size was 2.83 and the average family size was 3.27.
In the village the population was spread out with 26.5% under the age of 18, 4.7% from 20 to 24, 7.2% from 25 to 34, 42.6% over 45, 21.6% over 60 and 1.9% who were over the age of 85. The median age was 41 years. For every 100 females there were 90.5 males. For every 100 females age 18 and over, there were 84.1 males.
According to a 2007 estimate, the median income for a household in the village was $142,788, and the median income for a family was $164,486. The per capita income for the village was $53,196. The average earnings for a full time year round male is $93,144 and for a full time year around female the average earning is $49,954. About 104 families and 476 individuals below the poverty line poverty line, including 2.3% of those under age 18 and 2.6% of those age 65 or over.
There are five Long Island Rail Road (LIRR) train stations in the village that service Manhattan, Brooklyn and Long Island City. The stops on the LIRR Hempstead line are (moving eastward) Stewart Manor, Nassau Boulevard, Garden City and Country Life Press. There are additional stops on the LIRR Port Jefferson Branch at Merillon Avenue and just over the Garden City border at New Hyde Park and Mineola. Travel time to Manhattan ranges from 30 to 54 minutes, depending on the branch used.