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).