The U.S. Federal Census is taken every 10 years on a designated census day by an "enumerator" in a specific area called an enumeration district. The first census was done in 1790; there are no censuses before 1790.
The 1930 census lists the value of the property if owned, or the monthly rental if rented. This could lead to locating deeds, tax or mortgage records.
A military records subscription site is Fold3.com
Set up "proof files." These are your original documents that NEVER travel with you. Travel with copies if needed. Digital copies are easy to carry with you.
Short Tandem Repeat (STR): A short DNA motif (pattern) repeated in tandem. ATGC repeated eleven times would give the marker a value or allele of 11.