1910 census of Rowan Co., Ky, Hogtown precinct, enumerated 2 May, lists on p. 13A as family #208/209:
Nickell, Daniel B., 63, farmer, 2nd marriage, married 9 years; Samuel, 18, son; Albert, 10, son.

Although he is listed as married, not widowed or divorced, there is no wife in the household. The marriage number is also inconsistent with the record of his marriage to Lizzie Scaggs in 1902, which listed that as his third marriage.

There is a stone in Nickell-Harris Cemetery that says Mary Crum Nickell, 1848 - 1909. But in the 1900 census, Daniel Boone Nickell was married to a much younger wife, also named Mary E., with the number of years married given as 12. So either Mary Crum and Daniel divorced, or the year of death on her stone is in error.

Morgan Co., Ky, marriage records list the marriage on 25 Sep 1866 of Daniel P. Nickell and Mary Crum, at Daniel B. Nickell’s by M. L. Carter, witnesses James Goodman and John Brown.

1880 census of Rowan Co., Ky, Christy Creek precinct, enumerated 1 June, lists on p. 52 as family #360/387:
Nickell, Daniel, 31, farmer; Mary, 30, wife; Elijah, 11, son; John H., 9, son; William F., 6, son; Clarissa, 5, dau; Rosa E., 1, dau. All born Ky Ky Ky.