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.