Using the money he earned from working the ferry, he enrolled in Hanover College in 1839, but soon ran out of money to continue his education. His uncle offered to pay for the remainder of his school, provided that he would switch to a Methodist school. Porter agreed, and attended and graduated from Asbury University (now DePauw University) in 1843. The following year he moved to Indianapolis, Indiana, where he took a job in the state's auditors office and briefly served as a private secretary to Governor of Indiana James Whitcomb. Whitcomb influenced Porter to pursue a career in law, so he began to study law in the office of Philip Spooner. He was admitted to the Indiana bar in 1845 and entered a corporate law practice in Indianapolis headed by Hiram Brown. He met and married Brown's daughter, Minerva, on November 20, 1846. The couple had five children.