In 1852, McCulloch moved to Peoria, Illinois and opened a classical school in the basement of First Methodist Church.

In fall 1855, he was elected as a school commissioner for Peoria County, Illinois, a post he would hold for six years.

Building on his prominence as a prosecutor, McCulloch ran successfully for circuit judge, and was re-elected in 1879.

Shortly after he was re-elected, he was appointed to the Illinois Appellate Court, a post he held for six years.

In 1883, he ran unsuccessfully for a seat on the Supreme Court of Illinois, losing to Alfred M. Craig.