Mesa ( MAY-sə) is a city in Maricopa County, in the U.S. state of Arizona. It is the most populous city in the East Valley section of the Phoenix Metropolitan Area. It is bordered by Tempe on the west, the Salt River Pima-Maricopa Indian Community on the north, Chandler and Gilbert on the south along with Queen Creek, and Apache Junction on the east.

Mesa is the largest city by population in the United States without a large downtown. It is the third-largest city in Arizona after Phoenix and Tucson, the 37th-largest city in the US, and the largest city that is not a county seat. The city is home to 504,258 people as of 2020 according to the Census Bureau, which makes it more populous than Minneapolis, St. Louis, and Miami. Mesa has been described as “America’s most conservative city”.

More than 40,000 students are currently enrolled in more than 10 colleges and universities located in Mesa, including the Polytechnic campus of Arizona State University, Benedictine University, A.T. Still University, Upper Iowa University, Mesa Community College and Chandler-Gilbert Community College. Private for-profit institutions include Arizona College, Carrington College, DeVry University, Pima Medical Institute, and CAE Phoenix Aviation Academy. In January 2020, Arizona State University broke ground on ASU at Mesa City Center, a project offering programs from the Herberger Institute for Design and Arts that will be located in downtown Mesa that is scheduled to open in spring 2022. It is also home to the largest relief airport in the Phoenix area, Phoenix-Mesa Gateway Airport, which is in the southeastern corner of the city.