Having secured funding as "missionaries to the Missouri Territory," the Peck and Welch families traveled westward, arriving in
St. Louis in December, 1817. Peck and Welch organized the First Baptist Church of
St. Louis, the first Protestant church in the city, and baptized two converts in the
Mississippi River in February, 1818. By year's end, they also soon founded the first
missionary society in the West: The United Society for the Spread of the Gospel. In 1820, the
Triennial Convention, short of funds and convinced ministerial migration would continue, discontinued their missionary support. Peck refused to move back East or north to work with
Isaac McCoy among Native Americans. Instead, he continued his itinerant ministry and church-planting efforts around St. Louis independently. Two years later, the Massachusetts Baptist Mission Society employed Peck at $5.00 a week while conducting missions. Meanwhile, the St. Louis Baptists built a building with the Western Baptist Society on the first floor, and a meeting hall above (which they shared with Anglican, Methodist, Presbyterian and other Protestant denominations). Peck became active in establishing Bible societies and Sunday School associations. Distributing Bibles "silently undermine[d] the opposition to missions" of geographically stable preachers such as Daniel Parker, as well as spread literacy and Christian principles (including temperance and opposition to slavery) among the dispersed rural population. Peck moved to Rock Springs, Illinois in 1822 to farm, and arranged a circuit to visit the various societies which he continued to establish, as well as isolated farms. On one trip, Peck visited
Daniel Boone, then nearly 80, and later wrote a book about the frontiersman's life. In 1824 Peck's preaching helped Illinois Governor
Edward Coles defeat efforts to revise Illinois' constitution to permit slavery. Four years later, black Baptists in St. Louis sought to establish their own church, and with Peck's help they established the African Church of St. Louis (later renamed the First Baptist Church of St. Louis). Of the original 220 members, 200 were slaves. Peck ordained a young freeman,
John Berry Meachum, as their pastor. Peck then established the Illinois Baptist Education Society, serving as its first secretary. The
American Baptist Home Mission Society was organized in 1832, under Peck's influence, with Jonathan Going (sent from Massachusetts at his request the previous year) as the first secretary. This society, like Peck, directed its efforts toward the people of the frontier: Settlers,
Native Americans and later former
Confederate slaves. , Washington, D.C. Clockwise from top left:
James Madison,
John Leland, John Mason Peck,
Adoniram Judson,
Luther Rice Peck also helped establish the Illinois State Baptist Convention in 1834, and became its first president. He wrote prolifically, including on agriculture, frontier history and Native American matters. In 1843 he founded the American Baptist Publication Society. Peck also established a weekly religious journal, the
Western Pioneer. Harvard University awarded Peck an honorary degree in 1852. ==Death and legacy==