He also engaged in banking and in agricultural pursuits. He served as judge of Johnson County from 1882 to 1890. He was a member of the Illinois State Senate from 1890 to 1902.
Chapman was elected as a Republican to the Fifty-ninth. He was reelected to the Sixtieth and Sixty-first Congresses, and served from March 4, 1905, to March 3, 1911.
He was an unsuccessful candidate for reelection in 1910 to the Sixty-second Congress.
After leaving Congress Chapman resumed his legal, banking, business and farming interests. He was a delegate to the 1924 Republican National Convention.
He died in Vienna on January 31, 1931, and was interred in Vienna's Fraternal Cemetery.
