His name is also spelled as McLain in many records, perhaps more than have it as McClain, but it is easier for me to keep track of all the McClain/McLain/McClane families in the Fleming/Morgan/Bath/Rowan county area if I spell them all the same.

He must be the William McLain in this death record, since there was no other William McLain of the same approximate age who lived all his life in Fleming Co., but it has his parents wrong:

Kentucky death certificate records William McLain, age 87 years 9 months 26 days, born 11 June 1837 in Fleming Co., Ky, died 14 Apr 1925 in Fleming Co., Ky, father Howard McLain, born in Fleming Co., mother’s maiden name Mary Eden, born in Bath Co., cause of death lobar pneumonia, informant Edger Cooper, Ringos Mills, Ky.

I cannot find William in the 1860 census.

Her death certificate records Mary J. McClain, age 57, born 1860 in Fleming Co., died 16 June 1917 in precinct 7, Fleming Co., Kentucky, married, father Richard King, born in Bracken Co., mother’s maiden name Margrette Smoot, born in Fleming Co., cause of death paralysis of the insane, contributory cause cerebral hemorrhage, informant Chas Moltain, Ringos Mills, Ky, burial in Hillsboro Cemetery.

Fleming Co., Ky marriage book K, pp. 137-138, records the marriage on 2 Jan 1879 of William S. McClain, age 40, born in and both parents born in Bath Co., residence Fleming Co., his second marriage, to Mary J. King, age 18, born in and resident of Fleming Co., father born in Bracken Co,. mother born in Fleming Co., at residence of bride’s mother.

There is a consent note attached from Mary’s mother which reads:

“Farmville Fleming Conty Ky Jan the 1 1879
I have this day agree to let my Marry J. King have lison to marry the McLain this is stificuit
Margaret A. King
Attest
Belford Likes”

1880 census of Fleming Co., Ky, Hillsboro precinct, enumerated 15 June, lists on p. 21 as family #145/177:
McLane, William, 40, farmer; Mary J., 20; James E., 7/12, b. Oct. All born in Ky.

1900 census of Fleming Co., Ky, district 5, enumerated 16 june, lists on p. 10A as family #184/185:
McLain, William S., 60, b. June 1839, farmer; Mary J., wife, 39, b. June 1860, married 21 years, mother of 3 children, 2 living; Thomas L., son, 18, b. Nov 1881; Ninnie L., dau, 9, b. Jan 1891. All born Ky Ky Ky.

1910 census of Fleming Co., Ky, district 5, enumerated 29 April, lists on p. 10B as family #189/190:
McLain, William, 71, 2nd marriage, married 30 years, farmer; Mary J., wife, 50, 1st marriage, married 30 years, mother of 3 children, 2 living; Leslie, son, 29, farm hand; Ninnie L., dau, 19. All born Ky Ky Ky.

1920 census of Fleming Co., Ky, Hillsboro precinct, enumerated 4 Feb, lists on p. 15B as family #292/293:
Mclain, William, 81, widowed, farmer; Leslie, son, 38, single, farmhand. Both born Ky Ky Ky.

The next household is William’s daughter Nina with her husband Charles Molton.