Using LDS Family Seach Record Pilot Search I search Elijah Hanon 1800 to 1860. I find a Elijah Hanan b. 1827 in KY 1850 census of OH Ashtabula Co. Harpersville. Image of census page is available and looking at it I don't think it is KY but NY and I see name as Hannon not Hanan. I didn't remember this Elijah showing up in Ancestry's 1850 census result. So...
Going to Ancestry 1850 census Index and doing a first name only search of Eli*ah in Ashtabula Co OH thier result for the same census page as LDS Record search is Elijah Hannon age 23 b 1827 in NY.
I do not find this Eli*ah Hannon/Hanon/Hanan/Hamon born NY or KY b. 1827 plus or minus 5 yrs in an 1860 census except for the Elijah Homan in Peoria, IL also in the 1850 cennsus.
Using USGenWeb Project's Oregon, Marion County website link to U.S. Western States Marriage Index I find Elijah Hannon married Sarah Hale in Linn County, OR 1853, "Married at the residence of William Hale near Syracuse."
Using the USGenWeb Project's Linn County, OR link to Oregon State Archives Searchable database and searching Hanon and Hannon. Results are there is a Elijah Hannon in Linn County 1856 and 1857 Tax Rolls and in 1854 Marion Co Tax Rolls.
Have you tried the Internet Archive (www.archive.org) search Oregon and it has "Oregon Historical Quarterly" various volumes, to read and search online or other various ways to download results.