This cache is not at the posted coordinates, and neither location is an Oakland County Line.
The 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 (behind neighboring Wayne County), 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.
Woodward Avenue and the Detroit and Pontiac Railroad helped draw settlers in the 1840s. By 1840, Oakland had more than fifty lumber mills, processing wood harvested from the region and the Upper Peninsula. Pontiac, located on the Clinton River, was Oakland's first town and became the county seat. After the Civil War, Oakland was still primarily a rural, agricultural county with numerous isolated villages. By the end of the 19th century, three rail lines served Pontiac, and the city attracted carriage and wagon factories.
In the late 1890s streetcars were constructed here and operated between Detroit. This cache can be found at similar.linguists.pitied
At that time, developers made southern Oakland County a suburb of Detroit; a Cincinnati firm platted a section of Royal Oak called "Urbanrest". Migration worked both ways. Several thousand people moved from Oakland County farms to Detroit as the city attracted factories. By 1910, a number of rich Detroiters had summer homes and some year-round residences in what became Bloomfield Hills.
The auto age enveloped Pontiac in the early 1900s. The Oakland Motor Car Company was founded in 1907 and became a part of General Motors Corp., which was soon Pontiac's dominant firm. In the 1950s, Oakland County's population boomed as the Detroiters began migrating to the suburbs. While the neighboring Macomb County was more inhabited by auto workers and other blue-collar workers, Oakland County's residents tended to be more affluent and generally white-collar (e.g. doctors, lawyers).
The cache hide is pretty much exactly what you'd expect for the location you will arrive at.