Richard A. Wheeler writes, in the History of the Town of Stonington (1900), that the Mystic Congregational Church
was organized by thirty-seven seceding members from the First Congregational Church of Stonington, with five persons from other churches, on the 30th day of January, 1852, under the approval of a committee of the Consociation of Congregational Ministers and Churches of New London County[…..] The cornerstone of their present church edifice was laid with appropriate ceremonies Nov. 24th, 1859, and went on to completion and dedication. It was enlarged in 1869 by the addition of fourteen feet to its length.
Mystic Congregational Church (1860)