• Horace was born in New York.  He traveled to the Salt Lake Valley in the Brigham Young Pioneer Company in 1847 and was part of the 8th Company of Ten led by Seth Taft. According to Rockwood's journal, he was a member of the 20th Quorum of Seventies.  He was re-baptized in the Salt Lake Valley on 8 August 1847.   His birth and death dates are confirmed by his death certificate.

Brigham Young Vanguard Company (1847)

• Age at Departure: 24

Aaron Johnson Company (1850)

• Age at Departure: 28

Sources

• Albert P. Rockwood journals, 1847-1853, Journal, 1847 April-July.
• Heber C. Kimball journal in Heber C. Kimball papers, 1837-1866.
• Horace Thornton in The Book of the Pioneers Volume 2 (Utah Semi-Centennial Commission, 1897), 280.
• Journal History of The Church of Jesus Christ of Latter-day Saints, Supplement after 31 December 1850, 5.  
• "Member of First Band of Pioneers Called by Death," Deseret Evening News , 23 Mar. 1914, 12.
• "The Utah Pioneers," Deseret Weekly, 25 August 1894, 294.