Missouri · Central Time
557 Area Code
Area code 557 is in Missouri, serving St. Louis city and most of St. Louis County in eastern Missouri. It is in the Central Time zone. It shares its territory with overlay code 314, so 10-digit dialing is required.
Last updated October 1, 2026 · Source: NANPA
Where is the 557 area code?
557 is a Missouri area code covering St. Louis city and most of St. Louis County in eastern Missouri. In the wider directory it sits in the Midwest region.
Cities in the 557 area code
- St. Louis
- Florissant
- University City
- Kirkwood
- Maryland Heights
- Webster Groves
- Hazelwood
- Ferguson
- Creve Coeur
- Clayton
- Oakville
- Mehlville
- Affton
Counties served by 557
St. Louis County and City of St. Louis.
557 overlay codes and dialing
The 557 territory is covered by an overlay of 2 area codes: 314, 557. All of them serve the same geographic area, and the original code is 314. Because more than one code covers the same ground, 10-digit dialing is mandatory — you must dial the area code for every local call. New phone lines may be assigned any of these codes.
History of the 557 area code
557 went into service on August 12, 2022 as an overlay of 314, relieving number exhaustion in the St. Louis area. Rather than splitting the region, the overlay lets existing customers keep their numbers while new lines draw from the added code. Learn more in our overlay guide.
Is 557 a scam or spam risk?
557 is a legitimate geographic area code, not a premium or toll line, so a call from it costs you nothing extra. That said, scammers frequently spoof real local area codes to look familiar on caller ID. A genuine 557 number on your screen is no guarantee the caller is in St. Louis, MO or trustworthy. See spam & scam-risk area codes for how spoofing works and how to respond.
Other Missouri area codes
Explore more
See every code in Missouri, compare codes across the Midwest region, or view all Central Time codes. You can also browse the 5XX block or the complete numeric list of US area codes.
New to how this all works? Start with how area codes work, then read up on overlays, 10-digit dialing, and spam & scam-risk codes. To check another number, use the area code lookup tool.
Quick answers
557 area code FAQ
Where is the 557 area code?
The 557 area code is in Missouri, covering St. Louis city and most of St. Louis County in eastern Missouri, in the Midwest region.
What cities are in the 557 area code?
Cities in the 557 area code include St. Louis, Florissant, University City, Kirkwood, Maryland Heights, Webster Groves, Hazelwood, Ferguson, Creve Coeur and Clayton.
What time zone is 557 in?
557 is in the Central Time zone.
What is the overlay for the 557 area code?
557 shares its territory with 314. Both codes (314, 557) serve the same area, so 10-digit dialing is required for every call.
When did the 557 area code start?
557 went into service on August 12, 2022 as an overlay of 314.
Do I have to dial 10 digits for 557?
Yes. Because 557 is an overlay area, you must dial the full 10-digit number (area code + 7 digits) for every call.
Is 557 a toll-free or premium code?
No. 557 is a standard geographic area code, so calling it costs the same as any local or long-distance call on your plan. Toll-free calls use 800, 888, 877, 866, 855, 844 or 833.