Citizenship or Naturalization Records
The Archives of Michigan Naturalization Record Indexes has the naturalization/citizenship records for Kent County for 1860 - 1929. Records prior to 1860 no longer exist.
If one was naturalized through the U.S. District, Western District of Michigan (Grand Rapids), index cards with name, address and date of birth may still be located at 110 Michigan NW, Grand Rapids, MI 49503. Index cards exist only for events occurring around 1950 or later. The court may charge for any search. The actual records may have been sent to State Archives in Lansing.
State Archives of Michigan
717 West Allegan St.
Lansing, MI 48918