This family in Scott Co, Ontario in 1881 has a Jefferson Horner. He is a little older than the general age indicated on census records for Jefferson in 1910, 1920 and 1930 (by the way, Ancestry.com consistently indexes the family as HOMER rather than Horner, which is why they are difficult to find) but he was from Canada. The different censuses indicate that he came to the US sometime between 1890 and 1902 and he was a pipe fitter or steam fitter in all of the censuses. He does not appear in Fort Morgan in 1900, so perhaps the later date for immigration is correct. You can email me directly at gensearchers@shaw.ca if you would like copies of the censuses. The 1881 Canadian transcription is below.

Best wishes

Norm Dawson

Daniel S. HORNER M Male German 48 Ontario Carpenter Bible Christian
Eva HORNER M Female German 45 Ontario Bible Christian
William HORNER Male German 20 Ontario Farmer Bible Christian
Catherine HORNER Female German 18 Ontario Bible Christian
Elisabeth HORNER Female German 17 Ontario Bible Christian
Jefferson HORNER Male German 15 Ontario Bible Christian
Samuel HORNER Male German 14 Ontario Bible Christian
Albert HORNER Male German 11 Ontario Bible Christian
Wesley HORNER Male German 9 Ontario Bible Christian
James HORNER Male German 7 Ontario Bible Christian