The following history is taken from the City of Sycamore's official website (17 Aug 2011)
Sycamore has its origins in a claim established on the north bank of the East Branch of the Kishwaukee River, which was then called the Sycamore River, in 1835. The present location was surveyed as a village plat in 1836 and a county seat controversy was settled in Sycamore’s favor in 1839. That same year, Sycamore’s broad streets were laid out by Eli Barnes and James Waterman.
The surrounding prairie soils were particularly suitable for the raising of corn and by 1850 the population of 390 looked to the expanding rail network around Chicago as a vital link between local agriculture and a wider regional marketplace. In 1852, community leaders attempted to raise local subscriptions to build a rail line connecting Sycamore with the growing east-west rail traffic. This attempt failed and it was not until 1859 that Sycamore was linked with the prominent Galena and Chicago Railroad at Cortland for a cost of about $75,000.
In 1858 Sycamore was incorporated as a village and in 1869 the community was organized as a city. The Civil War that divided and ultimately transformed the country in the 1860’s had a salutary effect on the town’s growth. By the early 1880’s Sycamore had developed a substantial industrial base including the Marsh Harvester Manufacturing Company, the Reuben Ellwood Manufacturing Company, and the Sycamore Preserve Works. Though not extensive, this manufacturing presence helped push the city’s population to 3,300 in 1900.
As at the turn of the nineteenth century, the geographic, political, and social center of Sycamore remains the courthouse, central business district, and nearby historic homes. In no small way, the historic architecture and walkable business district convey a gracious charm that fits a popular image of the ideal small town.
As of the 2005 Special Census, Sycamore has grown to a population of 14,900.