Spencer is a small unincorporated crossroads in eastern Lawrence County, Missouri, United States. It lies along former U.S. Route 66 (now a county road) about six miles (10 km) west of Halltown. It started as a post office founded in the late 1870s on Carthage Road, later to become US 66. A store and church were built, but in 1912 the old road became impassable and the town dwindled. When US 66 was established, the town grew again, but the building of nearby Interstate 44 closed down the town to a couple of homes.