Blanding is a city in San Juan County, Utah, United States. The population was 3,394 at the 2020 census, making it the most populated city in S…Blanding is a city in San Juan County, Utah, United States. The population was 3,394 at the 2020 census, making it the most populated city in San Juan County. It was settled in the late 19th century by Mormon settlers, predominantly from the famed Hole-In-The-Rock expedition. Economic contributors include mineral processing, mining, agriculture, local commerce, tourism, and transportation.