Sewall K. Crocker (April 7, 1883 – April 22, 1913) was an American bicycle racer and automobile pioneer from Tacoma, Washington, who became the mechanic and co-driver who partnered with Horatio Nelson Jackson in the first successful cross-country automobile trip in 1903.

Jackson purchased a two-cylinder, 20-horsepower Winton motor car that he dubbed the Vermont for the journey, which was conceived following a $50 wager to prove that a four-wheeled machine could be driven across the country.

Crocker and Jackson departed San Francisco, California on May 23, 1903, and drove to New York City in about 63 days,[2] arriving on July 26.

Crocker was primarily responsible for making the necessary repairs of the vehicle during the trip, which broke down frequently, especially on the harsh, unpaved roads of the West.

After the race, Crocker attempted to capitalize on his fame by seeking sponsors for a round-the-world auto tour, but it never materialized.