Harvey is a Chicago area city in Cook County, Illinois, United States. The population was 30,000 at the 2000 census, but a 2003 Census estimate showed the population dropped to 29,367. 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.