In some parts of the United States people use town and city names when they talk about where they live or where things are located or where they are going. These people usually live in towns and cities and that is how they think about places.
However, many people live in rural areas - not in any town or city. These people often use counties, instead of cities when they talk about where they live or where they are going.
The lower the population density the more likely they are going to use counties instead of towns and cities. Why? Because the tiny towns and cities where they live are unknown to most people. Everyone has heard of Pittsburgh and Cleveland but nobody has heard of Gassaway and Erbacon, yet they probably know the name of the county if they live in that region.
People who live in cities "don't get it" when they hear rural people talking about what county they are from... but people who live in rural areas understand city people talking about what city they are from. This shows that rural people are smarter when it comes to geographic locations. 