Petroleum County ranks 56th out of 56 counties in the Treasure State for the total number of acres of land currently advertised for sale. Among cities in Petroleum County with farms, ranches, and rural real estate for sale, Winnett had the most land for sale. Its economy is defined as agricultural, with 100 farms recorded in the county during the most recent U.S. Census. Farming activities in Petroleum County generate annual revenues of $2 million, the majority of which comes from livestock products. Petroleum County is Montana's 42nd largest county (1,674 square miles). It's located in the North Central Montana region of Montana.