Hall accompanied his father to Randolph County, Missouri in 1840. There he studied law and was admitted to the bar at Huntsville in 1841 and commenced practice in Sparta in 1842. He was appointed circuit attorney in 1843 and served several years. Hall was a presidential elector on the Democratic ticket in 1844.

During the Mexican-American War he enlisted as a private in the First Missouri Cavalry and later was promoted to lieutenant; he was appointed by General Kearny, together with Col. Alexander Doniphan, to construct the code of civil laws known as the “Kearny code” in English and Spanish for the territory annexed from Mexico.

Hall was elected as a Democrat to the Thirtieth, Thirty-first, and Thirty-second Congresses, serving from March 4, 1847 to March 3, 1853. During his Congressional service he was the chairman of the Committee on Private Land Claims (Thirty-first Congress), and of the Committee on Public Lands (Thirty-second Congress).

He moved to St. Joseph, Missouri in 1854 and continued to practice law, being an unsuccessful candidate for election to the United States Senate in 1856. Hall was a member of the constitutional convention of Missouri in 1861 that determined the relations of Missouri to the Union and the other States and decided in favor of the Union. He served as provisional Lieutenant Governor of Missouri from 1861 to 1864. As brigadier general in the Missouri Militia, he commanded the northwestern Missouri district until 1863. He was Governor of Missouri in 1864 and 1865. After leaving office, he resumed the practice of law and died in St. Joseph in 1882. He is buried in Mount Moriah Cemetery.