Sycamore is a city in DeKalb County, Illinois, United States. It has a commercial district based and centered on Illinois Route 64. The population was 18577 at the 2020 census, up from 17,519 at the 2010 census. Sycamore is the county seat of DeKalb County and was named after the sycamore tree. History Early settlement The first European settlers to the Sycamore-area arrived in 1835 and concentrated themselves mostly north of the Kishwaukee River and the present site of Sycamore. The original town was platted by a New Yorker named Christian Sharer. A mill was constructed and the Kishwaukee dammed but the town failed. By 1837, after some controversy, the location of county seat was settled in favor of Orange, Sycamore's original name, and the settlement moved to the present-day site of the city. The present-day town site was platted by James Waterman and Evans Wharry in 1837 (the same year Chicago was founded). The first settler at the new site was Carlos Lattin, who preceded the town, having arrived in 1835. Lattin staked a claim that included most of the present west side of the city and erected his first cabin just north of downtown. County seat location Early in the city's history, it seemed that Sycamore might not be the location of the DeKalb County Courthouse: other towns were vying for the county seat title. A now-defunct town called Brush Point was the choice of a Dr. Henry Madden; and the Clerk of the Court Rufus Colton would have preferred Coltonville, where he made his home. Colton had set the first session of county court to be held at his home in Coltonville. In his attempt to make Coltonville the county seat, Colton decided to hold a new election for the status in 1837. Colton made sure that Coltonville would win the election by telling only the population of Coltonville about it. His political tactics were eventually cancelled by an act of the Illinois General Assembly, after the DeKalb County court intervened. When court convened the sheriff served a court order declaring Sycamore had built a Courthouse and that the Court session should be held there. Afterward, Coltonville eventually suffered the same fate as Brush Point and disappeared from the map. These events settled for a time the issue of where the courthouse and, in turn, the DeKalb County seat was going to be located. In 1903, as