All 300-Series Area Codes
Browse every active area code in the 300–399 range across the United States.
The 300-series brings together area codes from nearly every region of the country, with major metros anchoring much of the range — 312 in Chicago, 313 in Detroit, 305 in Miami, 303 in Denver, 317 in Indianapolis, and 346 in Houston all sit within these hundred numbers. Several of the country's largest cities have outgrown a single area code and now appear more than once across the group: Los Angeles is served by 310, 323, and 341, while New York City picks up both 332 and 347 as overlays added to handle decades of demand. The range also includes 340, the only US area code assigned to the Virgin Islands, anchored in the territorial capital of Charlotte Amalie. Smaller-metro codes like 308 in Grand Island, Nebraska and 364 in Bowling Green, Kentucky fill in around the major-city anchors, giving the 3xx range a mix of dense urban cores and quieter regional centers.
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