Draft registrations are just that: registrations. There is a difference between registering for the draft, being drafted, and volunteering.
Usually all men between a certain age were required to register when there was a draft registration. Some men were drafted. Some men volunteered.
If your male relative fit in the range of years of birth to register, you should check for a registration–even if he did not serve.
You can search World War Draft Registrations for US residents:
- World War I--at FamilySearch (read the “learn more” section if you’ve never worked with these before).
- World War II–old men’s registration for the draft–at FamilySearch (read the “learn more” section if you’ve never worked with these before). This is incomplete–you’ll have to browse.
- World War II–“young men’s” registration (these registrations cover the years 1940 to 1945 and includes information of young men aged 18-44. ). Some of these are on FamilySearch (visit their “US” page and click on your state of interest. Currently they only have cards for Louisiana and Maryland (they are called “first draft registration cards 1940-1945”). Some of these are at Ancestry.com (as an index “U.S. WWII Draft Cards Young Men, 1940-1947”) and Fold3.com as image (with index). Currently these sites have more of them than FamilySearch does.