I could not find John and Elizabeth Adams in the 1880 Alabama census yet their son, Frank, who is born in 1877 in Alabama should have shown and yet he does not either.
1900 Mobile, Mobile Co., Ala John Adams 2/1851 Canada(English) (parents: Canada) widower, immigrated 1873, driver grocery wagon Frank 3/1877 Ala (parents: Canada) motorman Willie 1/881 Ala (parents: Canada) driver grocery wagon Nettie 8/1884 Ala Henry 2/1892 Ala(aka Henry Richard) Amos 10/1893 Ala
1910 Mobile Will Adams 29 (married 11 yrs)b. Ala (parents: Ala) grocery clerk Hattie (wife) 27 (married 11 yrs, 2 children, 2 living) b. Ala (parents: Ala) Johnnie D. 10 Ala Antoinette 4 Ala John (father) 60 widower b. Ala (parents: Ala) drummer Henry 18 Ala shipping clerk Ernest 16 Ala apprentice machinist Oscar Sheppard (brother-in-law) age illegible, b. Ala (parents: Ala) carpenter
Death records of Alabama:John I Adams b. ca. 1850 d. 9/13/1911 in Mobile, Ala (may or may not be your John Adams)
1920 Mobile William Adams 39 Ala (f) Canada (m) USA grocery clerk Hattie 37 Ala (f) Denmark (m) Alabama John 20 Ala truck driver ship yard Nettie 12 Ala William 8 Ala Oscar 3 6/12 Ala Charles Lyons 50 (brother-in-law) b. Ala (parents: Ala) carpenter railroad shop Frank Adams 21 (nephew) b. Ala (parents: Ala) laborer ship yard James Adams 18 (nephew) b. Ala (parents: Ala) lineman electric company
1930 mobile William J. Adams 52 (married at 27) b. Ala (parents: Canada salesman wholesale bananas Hattie L. 43 (married at 17) b. Ala (f) Denmark (m) Ala John D. 30 (divorced) b. Ala salesman wholesale bananas L. Antoinette 22 Ala William A. 18 Ala order clerk Schartmart Store Oscar C. 13 Ala mail clerk newspaper Helen C. 9 Ala Dorothy L. 7 Ala
1940 Mobile Wm. Jos. Adams 61 Ala carpenter building Hattie 58 Ala Dorothy 17 Ala
I tried to trace back the 2 nephews shown residing with Willie/William in 1920 without success.
I could not find a death record for Elizabeth Wainwright Adams.She apparently died 1893-1899.A search of Mobile, Ala death records may give you an exact date and burial.
It appears that John and Elizabeth most likely married in Canada.