Area code 636

When the American Telephone and Telegraph Company (AT&T) created a universal North American telephone numbering plan for Operator Toll Dialing in 1947, Missouri was divided into two numbering plan areas (NPAs), which received the area codes 314 and 816.

By 1995, the telephone subscriber base experience substantial growth, threatening the exhaustion of the numbering pool.

Although area code splits were intended as long-term solutions, within only two years, 314 was close to exhaustion once again due to the proliferation of cell phones, fax machines and pagers in St. Louis.

As a result, 314 was reduced to include only the exchanges of Chestnut, Jefferson, Prospect, Flanders, Forest, Mission, Melrose, Webster Groves, Parkview, Evergreen, Riverview, Ferguson, Overland, Ladue, Kirkwood, Sappington, Mehlville, Oakville, Creve Coeur, Bridgeton, Hazelwood, Florissant, and Spanish Lake in the core of the St. Louis area.

[2] All other exchanges were reassigned to the new area code 636, effective May 22, 1999, with the permissive dialing period ending on February 26, 2000.