Door County is the easternmost county in the U.S. state of Wisconsin. As of the 2020 census, the population was 30,066. Its county seat is Sturgeon Bay. It is named after the strait between the Door Peninsula and Washington Island. The dangerous passage, known as Death's Door, contains shipwrecks and was known to Native Americans and early French explorers. The county was created in 1851 and organized in 1861.