[Capt. Tom]

I believe the following was in effect when Obama was born. also I believe the mother had to be over 14 years old.- Tom

"Congress has made it easier for unwed American mothers than it is for unwed fathers to pass on their citizenship. The foreign-born baby of an unmarried American mother is a U.S. citizen if the mother lived in the United States for at least one year."

http://articles.latimes.com/2010/nov/11/nation/la-na-court-citizenship-20101111

[PeaceBeWithYou]

In 1961, it was 10 years residency, 5 after the age of 14. So, 19.