Philadelphia County is the Delaware Valley's economic and cultural anchor and the ninth-largest combined statistical area in the nation with an estimated population of 7,381,180 as of 2022.

[2][circular reference] Native American tribes of Lenape were the first known occupants in the area that became Philadelphia County.

During the same year, Philadelphia was planned and was made the county seat and the capital of the Province of Pennsylvania.

Penn wanted Philadelphia, meaning "love brotherly", to be a place where religious tolerance and the freedom to worship were ensured.

[3] Philadelphia's name is shared with an ancient city in Asia Minor mentioned by the Bible's Book of Revelation.

It was William Penn's desire, as a Quaker, that his "Holy Experiment"[4] would be found blameless at the Last Judgment.

Philadelphia, as planned by Penn, comprised only that portion of the present-day city situated between South and Vine Streets and the Delaware and Schuylkill Rivers.

The city-county consolidation was a result of the inability of a colonial-type government by committees to adapt to the needs of a growing city for new public services, for example, better streets, police, transportation, sanitation, and schools.

In 1951, a new law known as the Home Rule Charter merged city and county offices completely.

This new charter provided the city with a common structure and outlined the "strong mayor" form of government that is still used.

Exceptions include restrictions stated in the Home Rule Charter of Philadelphia, Act of Consolidation, 1854, and subsequent legislation.

Presently, the city has some of the largest Irish, Italian, German, Polish, Puerto Rican, Korean, Vietnamese, Russian, Ukrainian, Jamaican, Chinese, Arab, Thai, and Cambodian populations in America.

The county has the fourth largest concentration of African Americans in North America, including large numbers of Liberians, Nigerians, and Sudanese.

The Northeast section of the city, and more significantly the suburbs of Philadelphia, contain large numbers of Indian Americans and Mexicans.

The lowest point in the county is 10 feet above sea level near Fort Mifflin in Southwest Philadelphia, at the convergence of the Delaware and Schuylkill Rivers.

Prior to the Act of Consolidation in 1854, a Board of Commissioners governed the county in accordance with the law of Pennsylvania at the time.

The origins of the Board of Commissioners are found in the office of Tax Assessor of Philadelphia County, established by an Act of the Pennsylvania General Assembly on November 27, 1700.

Subsequent acts passed by the Assembly in 1715, 1718 and 1722 increased the power and the scope of the Board, granting the Commissioners authority to share with the assessors in the assessment process and in the allocation of tax receipts among the various county projects, to participate in the appointment of the County Treasurer, and to issue warrants and levy fines against delinquent taxpayers and collectors.

Even though the governments of both the City and County were effectively consolidated by the Act of Consolidation, not all offices and agencies, such as the Board of Inspectors of the County Prison (Philadelphia Prison System), Coroner, Recorder of Deeds, and Sheriff, that were controlled by the county prior to the consolidation were transferred to the city, though their oversight and regulation were now managed by the City Commissioners.

The powers left to the Commissioners were chiefly accounting ones concerning county institutions, regulatory duties regarding weights and measures (given them by an Act of 1895) and administrative functions in association with elections, which culminated in complete control of their conduct with the formation of the County Board of Elections under their direction in 1937.