The "proof" that Obama was born in Canada is circumstantial. We have a University enrollment purportedly to be August 19, 1961 and we have the Statement from Ann's friend Susan Blake, that Ann came to visit her in Seattle in the later part of August, and did not know how to change a baby's diaper. Implying he was very recently born.
Other Freepers have found Flight rules for various airlines in 1961 that would have disallowed a woman with an infant from flying. (Supposedly the pressure changes would damage an infant's ear drums)
We also have the fact that Madeline Dunham and Stanly Dunham were very likely heavily racist in 1961. Coming from Kansas, they very likely would have been aghast at the thought of their daughter committing Miscegenation with a black man. (Still Illegal in Many states at the time.)
Madelyn Dunham's Co workers admitted that they didn't even know Madelyn Dunham had a grandchild until they found out he was running for the Illinois Senate. A woman who is proud of her grandchild does not refrain from telling her co-workers or even keeping a picture of him on her desk.
It has the "ring of truth" that Stanley Ann Dunham had been sent to live with her Aunt Eleanor Belle Dunham Berkebile who was living in Canada around this time, but latter lived in Blaine Washington. (Right across the border from White Rock Canada, where the only nearby Hospital was located. )
In 1961, it would have been perfectly reasonable to send a pregnant teenager (especially if pregnant by a black man) off to live with a relative until the baby came due. In fact, it would have been odd if they hadn't.
Barack Obama Sr did write that they intended to give the baby up for adoption.
The scenario of Barack Obama being born in Washington or Canada fits the available facts like a glove. It is a thoroughly plausible scenario.
I'd like to flesh out more detail, but I have to go. I have responsibilities to attend to.
bttt