Pima County county grew by 0.6 percent, and has now exceeded one million people in population for two years straight, reports the U.S. Census Bureau.
1,010,025 people called Pima County home in 2015.
Recent trends continued for Cochise and Santa Cruz counties in the 2015 population estimates. Both lost population for the fourth straight year.
Cochise County is down to 126,427 residents, a decrease of 0.7 percent. Cochise County's population drop in the last two years has been around 1.8 percent.
Santa Cruz County is now home to 46,461 residents, a drop of 0.4 percent. That is the smallest population drop for the county since 2012.
Pima County's growth is evenly split between natural growth (births and deaths) and migration.
Natural growth is pushing Santa Cruz and Cochise counties' populations upward, but net migration numbers show more people are moved out of the county than moved in.
Statewide numbers show Arizona grew by 99,282 people. Most of that growth, 78 percent, was in Maricopa County.