Thurlow Smith was born on November 16, 1918, in Oakley, Idaho, to Robert S. and Edna Louise Whittle Smith. The family worked a farm near Marion, which his grandparents settled after moving from Tooele, Utah, in 1881. In 1937 Thurlow graduated from Oakley High School where he played both basketball and football. He then earned a Teacher's Certificate from Albion State Normal School in 1939.

On July 29, 1940, Thurlow married Mary LaRene Butler, who he had met while at Oakley High School. Mary was born in Oakley, Idaho, on Christmas Day 1919, to George Andrew and Ida Butler. The couple had four children: Judith Ann, Denis Kay, Carol Jean, and Kevin Thurlow. LaRene went on to teach at Oakley Elementary School for 18 years.

After brief teaching stints at Declo and Sterling, Thurlow enlisted in the United States Navy where he served as a navigational instructor at Pensacola Air Base and worked in a flight control tower in Mobile, Alabama, during World War II. After returning home to Oakley in April 1946, he bought a small repair shop and service station and started an International Harvester dealership with his brother, Percy. In 1980 the company decided not to renew the dealership and Thurlow turned his focus to a farm north of Oakley and a cattle ranch in Little Basin.

An active member of his community, Thurlow served as a board member of the Oakley Canal Company, the Oakley Vigilantes, the Oakley Fire Department, the Cassia County Historical Museum, and the Oakley Swimming Pool construction. He was also a member of the local Chamber of Commerce, the City Board, and the American Legion Post 44, which he helped organize in 1946. Also active in the Latter-day Saints church, Thurlow served as Stake Clerk and High Councilman. He and LaRene served for 18 months in the Charleston, West Virginia Mission from 1983 to 1984.

Thurlow passed away in Burley, Idaho, on April 26, 2006. His wife, LaRene, preceded him in death.