Bloomington, the McLean County seat, took its name from the original settlement of Blooming Grove. The Illinois Republican Party was formed here in 1856 at the Anti-Nebraska convention, at which Abraham Lincoln made the famous "lost speech," spelling out the principles that were to elect him president. Bloomington was also the home of Adlai E. Stevenson, vice president under Grover Cleveland. His grandson, Illinois Governor Adlai E. Stevenson II, twice Democratic candidate for president and US Ambassador to the United Nations, is buried here.

Along with agriculture, the founding of Illinois Wesleyan University and the selection of North Bloomington (now the twin city of Normal) as the site for Illinois State University helped determine the town's economic future.