1860 US census schedule 2 for Salt Lake County includes enslaved individuals.
Salt Lake County Schedule 2 in the 1860 US Census, 1860, ancestry.com
John M. Hollady [slave owner]
[1 male slave]
[Unreadable] Box [slave owner]
[1 female slave]
Elizabeth Whitmore [slave owner]
[1 female slave]
J. J. Harper [slave owner]
[1 male slave]
Wm. A Hooper [slave owner]
[1 male slave]
Clifton Barnes
[2 female slaves]
N. R. Sprouse
[1 male slave]
Percilla Williams
[1 female slave]
Allima Williams
[1 female slave]
A. O. Smoot
[2 male slaves]
Geo Bankhead
[1 female slave and 6 male slaves]