The Upper Peninsula contains almost one-third of the land area of Michigan but just three percent of its total population. Residents are frequently called Yoopers (derived from "U.P.-ers") and have a strong regional identity. It includes the only counties in the United States where a plurality of residents claim Finnish ancestry. The peninsula's largest cities are Marquette, Escanaba, Sault Ste Marie, Menominee, and Iron Mountain. The land and climate are not very suitable for agriculture. The economy has been based on logging and mining. Most mines have closed since the "golden age" from 1890 to 1920, and the land is heavily forested. Logging remains a major industry.