<Tr> <Th> ZIP codes </Th> <Td> 850xx to 853xx, 856xx </Td> </Tr> <Tr> <Th> Area code (s) </Th> <Td> 623, 602, 480, 520, 928 </Td> </Tr> <P> The Phoenix Metropolitan Area--often referred to as the Valley of the Sun, the Salt River Valley or Metro Phoenix--is a metropolitan area, centered on the city of Phoenix, that includes much of the central part of the U.S. State of Arizona . The United States Census Bureau designates the area as the Phoenix - Mesa - Scottsdale Metropolitan Statistical Area (MSA), defining it as Maricopa and Pinal counties . As of the Census Bureau's 2015 population estimates, Metro Phoenix had 4,574,351 residents, making it the 12th largest Metropolitan Area in the nation by population . The gross domestic product of the Phoenix Metropolitan Area was $215 billion in 2014, 15th largest amongst metro areas in the United States . </P> <P> It is also one of the fastest growing major metropolitan areas, gaining nearly 400,000 residents from 2010 to 2015, and more than 1.3 million since 2000 . The population of the Phoenix Metropolitan Area increased by 45.3% from 1990 through 2000, compared to the average United States rate of 13.2%, helping to make Arizona the second fastest growing state in the nation in the 1990s (the fastest was Nevada). The 2000 Census reported the population of the metropolitan area to be 3,251,876 . </P>

What is the population of phoenix metro area