Area code 475 is an overlay of 203, covering southwestern Connecticut, including Bridgeport, New Haven, Stamford, and surrounding areas. It was introduced in 2009 to relieve number exhaustion in the densely populated and economically vibrant 203 region. The implementation of 475 made ten-digit dialing mandatory in all covered areas. Although newer, 475 is becoming increasingly common on mobile devices and among new residents and businesses. The area served by 475 includes some of Connecticut’s most populous and economically significant cities. Despite the rise of 475, many residents still associate the region with the legacy 203 code, but both now function interchangeably.