The 1860 Republican National Convention was a presidential nominating convention that met May 16–18 in Chicago, Illinois. It was held to nominate the Republican Party's candidates for president and vice president in the 1860 election. The convention selected former representative Abraham Lincoln of Illinois for president and Senator Hannibal Hamlin of Maine for vice president.

Chicago is the most populous city in the U.S. state of Illinois and in the Midwestern United States. With a population of 2,746,388 in the 2020 census, it is the third-most populous city in the United States after New York City and Los Angeles. As the seat of Cook County, the second-most populous county in the U.S., Chicago is the center of the Chicago metropolitan area, often colloquially called "Chicagoland" and home to 9.6 million residents.