Phoenix City, located in the state of Arizona, belongs to Maricopa County. This classification is based on the administrative boundaries set by the state government. According to the United States Census Bureau, Maricopa County encompasses a total area of 9,224 square miles, with Phoenix being the largest city within its borders. The city of Phoenix itself spans approximately 517 square miles and is the sixth-largest city in the United States by population.

The reason for this classification lies in the hierarchical structure of local government in the United States. Each city is a political entity within a county, which is a larger administrative division. Maricopa County, established in 1861, is one of the most populous counties in the country, with a population of over 4.9 million as of the 2020 census. Phoenix, as the county seat, serves as the administrative center and hosts numerous county government offices.

Data from the U.S. Census Bureau indicates that Maricopa County is characterized by its rapid population growth, particularly in the past few decades. This growth has been driven by factors such as favorable climate, economic opportunities, and a strong housing market. As a result, Phoenix has become a major metropolitan area, contributing significantly to the county's population and economic activity.

Moreover, the city of Phoenix has a diverse economy, with a strong presence in sectors such as healthcare, retail, and manufacturing. This economic diversity has helped the city to thrive within the broader context of Maricopa County. The close relationship between Phoenix and Maricopa County is further exemplified by the numerous intergovernmental agreements and collaborations that facilitate the provision of public services and infrastructure development.

In conclusion, Phoenix City is an integral part of Maricopa County, reflecting the complex web of local government structures in the United States. The city's growth and economic contributions have solidified its position as a key player within the county's administrative and economic landscape.