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.

[3] The present-day town site was platted by James Waterman and Evans Wharry in 1837 (the same year Chicago was founded).

[3] Lattin staked a claim that included most of the present west side of the city and erected his first cabin just north of downtown.

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.

[5] In his attempt to make Coltonville the county seat, Colton decided to hold a new election for the status in 1837.

His political tactics were eventually cancelled by an act of the Illinois General Assembly,[4] after the DeKalb County court intervened.

[4] These events settled for a time the issue of where the courthouse and, in turn, the DeKalb County seat was going to be located.

Two of DeKalb's most prominent citizens, Jacob Haish and Isaac L. Ellwood, each promised to donate $20,000 to help absorb some of the new building's cost.

Following the American Civil War the railroad began to assist Sycamore's growth and the settlement was incorporated as a city in 1869.

She was last seen by her playmate Kathy Chapman (née Sigman) with a young man who called himself "Johnny" and had approached the girls offering them piggyback rides.

The case remained unsolved for over 50 years until in 2011, Jack Daniel McCullough, a former neighbor of the Ridulphs, was arrested and convicted of kidnapping and murdering Maria.

[6] However, in April 2016, McCullough's conviction was overturned and he was released from prison after a post-conviction review of the evidence indicated that he could not have committed the crime.

[11] The terrain in Sycamore and the surrounding area is gently rolling and contains rich soil which was originally heavily forested.

The district is composed of two-story shops, a bank, small movie theater, and former Midwest Museum of Natural History.

The lawn of the DeKalb County Courthouse is the center of the event and includes a display of decorated and carved pumpkins.

[13] The event attracts thousands to Sycamore from locations throughout northern Illinois, the Midwest, and the broader United States.

[13][14][15] The city is also home to the Sycamore Historic District, an architecturally interesting area containing over 200 individual properties.

[17] Sycamore is also home to the former Midwest Museum of Natural History, which featured a varied taxidermy collection and closed in February 2020.

The newest elementary school, North Grove, opened in 2009 was built for access by the nearby subdivision.