While in Chicago, Charles Sr. became superintendent of the Sunday school at the
North Presbyterian Church, and there met the inventor
Cyrus Hall McCormick, whose mechanized reaper did for the Midwest what the cotton gin had done for the South. The two remained close friends and kept up an extensive correspondence until McCormick's death in 1884. Spring and McCormick established the South Church in what is now
The Loop in Chicago, although they returned to the North Church when they were able to retain their favoured pastor, Rev. Dr.
Nathan Rice. During the 1850s, Charles was instrumental in the founding of what eventually became the
McCormick Theological Seminary. McCormick was a conservative Democrat who had been born in Virginia, and although he was no apologist for slavery, was intent on holding together both the Old School
Presbyterian Church and the Union (he considered the Presbyterian Church and the Democratic Party to be the “two hoops that hold the barrel of the Union together." McCormick thus set his sights on securing a seminary which would advance orthodox Presybyterian doctrine. An Indiana seminary was in dire straits, and when the General Assembly met in Indianapolis in 1859 to discuss its future, McCormick, acting through Spring (who was a delegate), offered the seminary an endowment of $100,000 on the condition that the Seminary locate in Chicago and that the General Assembly take control of it from the synods. This was an offer that the General Assembly couldn't refuse, and so the Seminary found its new home in Chicago. Charles A. Spring was also instrumental in gaining the donation of some of the land for the seminary, from the brewers Lill & Diversey. He sat on the Seminary's Board of Directors from 1859 to 1876 (when he relocated to Western Iowa). In an 1872 letter, McCormick gave his friend Spring the credit for the founding of the seminary, referring to Spring as “the most aged and experienced of us all, and to whom I was myself indebted for the original suggestion and advice to make the donation to this cause", the seminary. In 1859, Charles guided the creation of the First Presbyterian Church of
Manteno, Illinois, securing a donation from McCormick which funded nearly half of the amount necessary for the building of the church. In 1866, he gave the parsonage as a gift (it burned down soon after his death, in 1895). In 1861, Charles was a delegate to the Presbyterian General Assembly in Philadelphia which considered the Gardiner Spring Resolutions propounded by his brother, Rev. Gardiner Spring, of New York City. The assembly finally approved the resolutions, which meant the church would stand behind
Abraham Lincoln's attempts to keep the Union intact. In 1865, Spring cared for
William Sanderson McCormick, the inventor's brother and partner, during his long illness. When William died that fall, Charles A. Spring Jr. took over the management of the McCormick Co., as well as McCormick's extensive real estate holdings. The elder Spring often helped his son in this, especially during the busy spring leasing season. Charles Sr. repeatedly tried to convince McCormick to carry out one of William's last wishes, which was to found a home for young girls (age 5–10) to save them from “destructive Parental & other influence” and to clothe, feed, and educate them in a religious environment. Charles himself had successfully petitioned the Chicago City Council to set aside funds to establish the Chicago Reform School for Boys, one of the first of its kind in the nation. According to Hutchinson, McCormick's biographer, Charles believed that “too much emphasis was placed upon punishment, and not enough upon the prevention of crime. ==Later life==