Besides financing construction of the new Courthouse, the Kane County Board faced other budgetary problems as the Civil War required a continual outlay of men and money. In July, 1861, the Board appointed a War Committee which appropriated money for horses, bounties, equipment for the troops, and family benefits. The hundreds of men from Kane County who volunteered to serve in the Civil War attest to Kane County's involvement in the war operations. The names of these men are preserved in a plaque on the monument in front of the present Courthouse in Geneva.

The years following the Civil War were marked by a sudden increase in population as people came to the area looking for jobs in the mills and factories which were built along the Fox River. The railroads also played a significant part in the growth of Kane County as the first line in northern Illinois crossed Elgin and continued south to Geneva. This was the Galena and Chicago Union Railroad which linked the lead mines on the Mississippi River with the Chicago industrial area. This line eventually became the Chicago and North Western Railroad which has run through Kane County since 1853.

Aurora was also a major railroad center with the Chicago, Burlington and Quincy Railroad, now the Burlington Northern, operating through Aurora. The old roundhouse still stands on North Broadway. and has been converted to a restaurant and micro-brewery.

Other railroad lines connected the river towns with each other, as well as the Chicago metropolitan area.

The railroad was also instrumental in establishing Kane County as a prominent dairy region around this time. The Chicago hotels were a major consumer for the milk, butter and cheese from the northern Kane County area and the railroads provided rapid transportation for the fresh dairy products which were shipped daily into the city. The Elgin Board of Trade established butter prices throughout the entire country.

Kane County continued its rapid growth during the 1900's. The population doubled from 65,000 to 130,000 during the 50-year period from 1890 to 1940. The population doubled again to 260,000 in the next 30-year period to 1970, along with the increasing number of industries, medical centers, and educational institutions. In 1967, the United States government built Fermilab, a center for energy research and development, on a 6,800 acre site outside Batavia. This research center provides educational and cultural opportunities for residents of Kane and surrounding counties.

According to the census bureau, as of 2002 Kane County's population is estimated to be over 443,000 and is steadily increasing due largely to expansion from the Chicagoland area. More Kane County farm lands are being rezoned to fit the demand of housing construction.

The Kane County Board is now struggling with the problem of maintaining the traditional beauty and open spaces of Kane County despite the pressures for rapid development of the agricultural areas. The decisions made today will influence the future growth of Kane County.