[6] It is by far Arizona's most populous county, encompassing well over half of the state's residents.

[7] In October 2022, Maricopa County Environmental Services Department detected Dengue virus in mosquitoes they had trapped; in November the first locally transmitted case of dengue fever was reported in the County and Arizona state as a whole - previous dengue cases in Maricopa County had been related to travel.

The Maricopa County Board of Supervisors consists of five members chosen by popular vote within their own districts.

While the city of Phoenix has been evenly split between the two major parties, most of the rest of the county was strongly Republican.

This includes the 1964 presidential run of native son Barry Goldwater, who would not have carried his own state had it not been for a 21,000-vote margin in Maricopa County.

[26] Furthermore, Biden became the first presidential candidate to win more than one million votes in the county.

In 2024 however, Trump was able to flip the county back as he carried Arizona in that election due to his increase in support among Hispanics in Phoenix and its suburbs.

Despite its consistent Republican allegiance since 1952, its fast-growing Hispanic population and influx of conservative retirees and Mormons, which were traditionally conservative voting blocs but were increasingly skeptical of President Donald Trump, signaled that it was a crucial bellwether in the 2020 election.

[27] Despite its political leanings at the time, Maricopa County voted against Proposition 107 in the 2006 election.

Two years later, however, a majority of county residents voted to pass a more limited constitutional amendment Proposition 102 to ban same-sex marriage but not state-recognized civil unions or domestic partnerships.

The amendment was later invalidated by the Supreme Court's 2015 ruling in Obergefell v. Hodges, which declared that same-sex marriage is a fundamental right in the United States.

Unlike cities and towns in Arizona, counties are politically and legally subordinate to the state and do not have charters of their own.

The county Board of Supervisors acts under powers delegated by state law, mainly related to minor ordinances and revenue collection.

The county's dominant political figure for over two decades (from 1993 to 2017) was Sheriff Joe Arpaio, who called himself "America's Toughest Sheriff" and gained national notoriety for his flamboyant and often controversial practices and policies.

[30] Maricopa County is home to 62 percent of the state's population and therefore dominates Arizona's politics.

Conversely, in the 2024 General Election, former president Donald Trump won Maricopa County by 71,515 votes and won the state of Arizona by 187,382 votes, making the 5.5 percent statewide victory the largest percentage win of any of the seven 2024 swing states.

Other airports located in the county include: In terms of freight rail, the Union Pacific Railroad and the Burlington Northern Santa Fe Railroad serve the county.

The train connects Maricopa to Tucson, Los Angeles, and New Orleans three times a week.

The population ranking of the following table is based on the 2020 census of Maricopa County.

The county also ties for the highest amount of cling peach with Cochise,[44]: 300  along with Pima produces almost all the pomegranate,[44]: 302  and grows most of the kumquat.

[44]: 302  Maricopa's farms grow a middling amount of fig,[44]: 299  grape (Vitis spp.

[44]: 301 All of the boysenberry,[44]: 307  half of the elderberry (along with Yavapai),[44]: 307  and a small amount of the state's blackberry[44]: 307  and strawberry[44]: 308  are harvested here.