Oakland County is a county in the U.S. state of Michigan. It is a principal county of the Detroit metropolitan area, containing the bulk of Detroit's northern suburbs. Its seat of government is Pontiac, and its largest city is Troy. As of the 2020 Census, its population was 1,274,395, making it the second-most populous county in Michigan, and the most populous co…Oakland County is a county in the U.S. state of Michigan. It is a principal county of the Detroit metropolitan area, containing the bulk of Detroit's northern suburbs. Its seat of government is Pontiac, and its largest city is Troy. As of the 2020 Census, its population was 1,274,395, making it the second-most populous county in Michigan, and the most populous county in the United States without a city of 100,000 residents. Founded in 1819 and organized the following year, Oakland County is composed of 62 cities, villages, and townships. In 2010, Oakland County was among the ten wealthiest counties in the United States to have over one million residents. It is also home to Oakland University, a large public institution that straddles the border between the cities of Auburn Hills and Rochester Hills.