Harvey is bordered by Dixmoor, Riverdale and Blue Island to the north, Posen and Markham to the west, South Holland, Phoenix, and Dolton to the east, and East Hazel Crest to the south.
Three major north-south streets in Chicago venture as far south as Harvey in some capacity. Halsted Street (Illinois Route 1) runs through the east side of town. Dixie Highway, as it is known in Harvey, is Western Avenue in Chicago. Finally, Chicago's Ashland Avenue becomes Wood Street in Harvey. The reason for this is a surveyor's error along the line where Interstate 57 is now located; Harvey's street names and numbers conform to the section lines rather than actual distance from Chicago's base lines (as indicated by the jogs in Halsted Street near 150th Street and 159th Street between Harvey and Markham, as examples). Harvey's own Ashland Avenue serves as the east-west dividing line for house numbering.
As of the census of 2000, there were 30,000 people, 8,990 households, and 6,760 families residing in the city. The population density was 4,842.2 people per square mile (1,868.2/km²). There were 10,158 housing units at an average density of 1,639.6/sq mi (632.6/km²). The racial makeup of the city was 79.57% African American, 10.02% White, 0.26% Native American, 0.38% Asian, 0.05% Pacific Islander, 7.94% from other races, and 1.78% from two or more races. Hispanic or Latino of any race were 12.78% of the population. There were 8,990 households out of which 39.1% had children under the age of 18 living with them, 36.4% were married couples living together, 31.8% had a female householder with no husband present, and 24.8% were non-families. 20.7% of all households were made up of individuals and 7.1% had someone living alone who was 65 years of age or older. The average household size was 3.30 and the average family size was 3.80.
In the city the population was spread out with 35.1% under the age of 18, 10.8% from 18 to 24, 26.7% from 25 to 44, 18.8% from 45 to 64, and 8.6% who were 65 years of age or older. The median age was 28 years. For every 100 females there were 92.2 males. For every 100 females age 18 and over, there were 86.0 males.
The median income for a household in the city was $31,958, and the median income for a family was $35,378. Males had a median income of $30,610 versus $25,248 for females. The per capita income for the city was $12,336. About 20.3% of families and 21.7% of the population were below the poverty line, including 27.8% of those under age 18 and 17.6% of those age 65 or over.
Harvey is serviced by two stations along the Metra Electric University Park line to Chicago. One is at 147th Street(a.k.a. Sibley Boulevard) & Clinton Street, and the other is at Park Avenue & 154th Street.