The area code 557 is located in St. Louis, Missouri.
Area code 557 serves the same footprint as 314 in St. Louis, Missouri, covering the city and many inner-ring suburbs along the Mississippi River. It reaches key landmarks like the Gateway Arch, Busch Stadium, and Forest Park, keeping residents, schools, and businesses connected across the urban core. This code was introduced as an overlay to expand available phone numbers without changing local boundaries, so it simply coexists with 314. For callers, that means the region uses 10-digit dialing for local calls.
As an overlay, 557 does not replace 314; both area codes cover the same geography, and existing numbers stay the same. The overlay was added in the early 2020s to meet demand from mobile phones, VoIP lines, and new businesses across the metro. “An overlay adds a new area code to the same geographic area; existing telephone numbers do not change.” — FCC. St. Louis’s long-running 314 (one of the original 1947 area codes) remains active, while 557 helps supply fresh numbers for the future.
Expect the same calling area and rates as 314, with new lines possibly receiving a 557 prefix. The region includes major highways (I‑64, I‑70, I‑44, and I‑55) and a strong mix of healthcare, education, logistics, and tech, making reliable numbering essential. If a number shows area code 557, it’s a St. Louis metro line—covering the city’s historic neighborhoods, cultural attractions, and busy business districts.