John shows up on ancestry.com in the Missouri Western District Naturalization Index. He gives his birthdate as 24 Aug 1884; says he arrived in port of NY on 6 Apr 1906. He was naturalized on 9 Nov 1925.
In the 1925 Kansas State Census, John says he came to Kansas from Illinois; Minnie says she came to Kansas from Missouri. I wonder if that means they were married in Kansas?