Bangor is a city in and the county seat of Penobscot County, Maine, United States. The city proper has a population of 31,753, making it t…Bangor is a city in and the county seat of Penobscot County, Maine, United States. The city proper has a population of 31,753, making it the state's third-most populous city, behind Portland and Lewiston. Bangor is known as the "Queen City."