The City of Lake St. Louis is a planned community situated around two lakes amid Interstate 70 and Interstate 64 in western St. Charles County, Missouri, United States. The population was 16,707 as of the 2020 US Census.

In January 1961, Ellis Ellerman and Ira Nathan begin developing plans for a private resort community, a popular concept in the 1960s in the St. Louis region. The vision was for a weekend resort considering a lake large enough for recreation and a location near to St. Louis. Ellerman and Nathan hired engineers to begin the initial planning of the lake and community, and Nathan named the project “Lake St. Louis” in 1961.

Ellerman and Nathan formed Trails Lake Development Corp. in 1962, and by August 31 of that year, 10 lots had already been sold in the project, which was to feature a 625 lake (PD article 8-25-63). Ellerman and Nathan lacked normal financing and issue experience, and they soon found themselves in over their heads on the project. Ellerman and Nathan were soon allied by several supplementary investors to save the project afloat, including R. T. Crow. The financial troubles continued for Ellerman and Nathan, and The Healey Discount Corp., owned by Crow and the three further investors, foreclosed upon Ellerman and Nathan’s Trails Lake Development Corp. in June 1966.

R. T. Crow felt the location of “Lake St. Louis” (indicating a amend of ownership and the “planned community” concept), between two major highways, I-70 and Rt. 61, and the westward growth of St. Louis justified building a new town, rather than just the weekend community envisioned by Ellerman and Nathan. He investigated the idea of additional towns, including visiting many others in the east. In the end, Crow bought out the additional three investors who were share of The Healey Discount Corp., and he became the sole developer of the Lake St. Louis development. St. Charles County ascribed the preliminary intention for Lake St. Louis in April 1967. People who had purchased lots from the first developers were unchangeable credits for lots in the extra Lake St. Louis project.