Illinois was easily won by sitting Vice President Al Gore of the State of Tennessee, unlike other states in the Midwest, such as nearby Iowa, Michigan, Minnesota and Wisconsin, which Gore won, albeit by much smaller margins. George W. Bush, Republican of Texas, did not perform terribly at the county level, as he obtained less than forty percent of the vote in only three counties. Gore's key to victory was Cook County, home of Chicago, by far the most populous county in the state and one of the most populated counties in the nation. Gore won that county with almost seventy percent of the vote, his best performance in any county in the state.[1]
The election marked the first time since 1976 that Illinois did not vote for the winning presidential nominee and marked an end to Illinois’ status as a bellwhether state, as it had voted for the winning candidate all but two times in the 20th-century, making it tied with Missouri as having the most consistent streak of backing the winner in that century. Bush became the first Republican to win the White House without carrying Illinois; he also became the first Republican ever to win the White House without carrying Champaign, Peoria, or Whiteside Counties.[2] It was additionally the first election in which the Republicans outperformed in Southern Illinois, a previous Democratic stronghold. This was also the first time since 1848 that a Democrat would carry Illinois without winning the presidency.
Illinois was one of ten states that backed George H. W. Bush for president in 1988 that didn't backed George W. Bush in either 2000 or 2004.