Interesting. Would you happen to have a link to your sources? Thanks.
A good answer here: http://uclue.com/?xq=379
Toward the bottom of this one: http://www.sovereignfellowship.com/tos/21.28/
This misses the mention of actual name of the laws: http://en.wikipedia.org/wiki/Marriage_licence
There are lots of articles on the subject, the practice of licensing was not universal in all municipalities in the US until this- “In 1923, the Federal Government established the Uniform Marriage and Marriage License Act (they later established the Uniform Marriage and Divorce Act). By 1929, every state in the Union had adopted marriage license laws.”
This is a good article as well: http://www.lewrockwell.com/mcmaken/mcmaken86.html