U.S. Highway 1 (US 1) in Florida runs 545 miles (877 km) along the state's east coast from Key West to its crossing of the St. Marys River into Georgia north of Boulogne and south of Folkston. US 1 was designated through Florida when the U.S. Numbered Highway System was established in 1926. With the exception of Monroe County, the highway runs through the easternmost tier of counties in the state, connecting numerous towns and cities along its route, including nine county seats. The road is maintained by the Florida Department of Transportation (FDOT).

Monroe County is a county in the state of Florida. As of the 2020 census, the population was 82,874. Its county seat is Key West. Monroe County includes the islands of the Florida Keys and comprises the Key West-Key Largo Micropolitan Statistical Area. Over 99.9% of the county's population lives on the Florida Keys. The mainland, which is part of the Everglades, comprises 87% of the county's land area and is virtually uninhabited with only 17 people recorded in the 2020 census.