Price came to central Missouri in 1831. A Democrat, he was elected to the general assembly of Missouri in 1836. He was re-elected in 1840 and 1842 and, at each session, chosen speaker of the house. In 1844 he was elected to Congress and served until the opening of the war with Mexico, when he raised a regiment and had an independent command in New Mexico and Chihuahua. He gained victories over greatly superior forces at Cancada, Lambonda and Taos. In this last battle, his 300 men captured 1,500 prisoners. For these services President Polk appointed him a brigadier-general.

Moving next against Chihuahua, at Santa Cruz de Rosales, he captured the army of General Trias, which was twice the size of his own. This was really the last battle of the war; for a treaty of peace between the United States and Mexico had been signed a short time before. At the next state election General Price was elected Missouri´s 11th governor by a majority of 15,000 votes. Shortly after the "Camp Jackson Affair" he was appointed commander of the state militia, but he left the Union cause and served throughout the war as commander of the Missouri Confederate forces. Price established a colony of Missouri Confederate veterans in Mexico at the end of the war, but returned to Missouri in 1866 and died in St. Louis a year later. His grave is in Bellefontaine Cemetery.