Land for sale in Foster County, North Dakota, recently totaled approximately $400,000 and nearly 1,000 acres. Foster County ranks 40th in North Dakota for the combined amount of land currently advertised for sale. Mchenry had the most land for sale. Foster County has a large agricultural economy, with 310 farms recorded in the county during the latest U.S. Census. Farming activities in Foster County generate annual revenues of $6 million, most of which is from crops. Foster County is North Dakota's 52nd biggest county (646 square miles). It's located in the Southeast North Dakota region of the state.