Merrill's career included government service as a representative in the
Indiana General Assembly (1821–22) and as the
Indiana State Treasurer (1822–34). He was also involved in banking and other business ventures. Merrill was president of
State Bank of Indiana (1834–44) and the
Madison and Indianapolis Railroad Company (1844–48). He also owned an Indianapolis bookstore and publishing company that later became the
Bobbs-Merrill Company.
State legislator and treasurer Merrill moved to
Vevay, Indiana, in 1816, and was elected to the
Indiana General Assembly in 1821 as the representative of
Switzerland County. While serving in the state legislature, Merrill was elected as
Indiana State Treasurer. After the decision was made to relocate the seat of state government on January 20, 1824, Merrill had a role in helping to the name the new state capital. He seconded the motion to adopt the name of
Indianapolis for the state capital of Indiana. Merrill also oversaw the transfer of the state treasury and state government's records to
Indianapolis from
Corydon. The arduous task included Merrill's and his young family's eleven-day journey of about by horseback and wagon caravan from Corydon to the new state capital in November 1824. Merrill's caravan of four, four-horse wagons and two or three saddle horses brought the state treasury, governmental records, a printing press, and furniture for the Indiana General Assembly, the Indiana Supreme Court, and the state's executive offices, as well as two families, including his own, their personal goods, and implements and supplies for the caravan. He also arranged for the transfer of the state archives and state library to Indianapolis. After relocating to Indianapolis, Merrill and his family lived in a two-story brick building, later demolished, that the state government had constructed at the southwest corner of Washington Street and present-day Capitol Avenue to house the state treasurer's office and residence, as well as the state auditor's office. Merrill continued to serve as state treasurer until 1834, when he was named president of the
State Bank of Indiana. He was also a partner in the trading firm of Yandes and Merrill and was active in other business ventures and civic affairs.
Railroad company president Merrill served as president of the Madison and Indianapolis Railroad Company from 1844 to 1848. With additional funding from investors in the
East, Merrill expanded the railroad to complete the line, which extended from
Madison, Indiana, to Indianapolis. More track was laid during his first two years as president than had been done in the previous ten years of its state-owned management. Merrill resigned from the railroad in 1848 after disagreements with H. R. Hall, the rail line's superintendent. The following year he bought Hood and Noble's bookstore, one of four bookstores located in Indianapolis at that time, and oversaw its merger with his publishing business. ==Other interests==