Area code 636 serves the western suburbs of St. Louis, Missouri, including cities like St. Charles, Chesterfield, and O’Fallon. Introduced in 1999 as a split from 314, it supports a region of growing suburban development and economic activity. St. Charles County is one of Missouri’s fastest-growing areas, offering a mix of family-friendly neighborhoods, retail centers, and light industrial zones. Chesterfield, in particular, is known for its affluent population and commercial appeal. Major employers include healthcare providers, logistics companies, and manufacturers. The area also features excellent schools, expansive park systems, and easy access to downtown St. Louis via I-64. A 636 number positions businesses within one of the state’s most dynamic suburban corridors, appealing to both professionals and families.