Hi, no I don't think it is the same family, but I have found McCullums in Davis Co. Iowa. Just not sure where I found them. I do alot of work on usgenweb.org or maybe familysearch.org this may have been where I found them. Frank McCullum, who I was searching for, I have found. He was the child of Hamilten and Susun (Ludington) McCullum and the grandchild of William and Jane McCollum
( the spelling of the name was changed sometime after 1894)and the great grandchild of Alexander & Susannah McCollum. they all came over to New York From Northern Ireland sometime around the 1850's to Elbridge New York
( Onandoga Co.) then on to Iowa. (Pocahontes/ Humboldt Coo.) Alexander and Jane did have 10 children and William and Jane had 9 but I didn't see a Macum I have also found Mccullums in Apanoose Co. Sac Co. and Clay co ( none related or no connection made so far but maybe for you. Good luck in your search. may find out we are related after all (^: