Thanks for all the answers. It's not impossible that my mother renounced her Canadian citizenship when she became an American. She no longer remembers, but she wouldn't have done it on her own, it would probably have depended on what the US rules were at time. Nonetheless, I'm contemplating applying for a citizenship certificate and paying the $75 fee. There doesn't seem to be a way to ask the question, "Am I a citizen?" without going through the application process.
When I went to Canada in the 70's I was told that if I applied for Canadian citizenship I would have to renounce my US citizenship as the US only allowed you to be of one nation at that time.
This has since changed, and our son, born in Canada of 2 US citizens is a dual, now living in Vancouver, BC.
We used to be "landed immigrants" in Canada and had SIN cards. That classification has now changed, and it appears we lost our status when we returned to the states. We are collecting CPP (Canadian social security) from working there for 18 years. And file taxes ...
Also thinking of renewing and applying ... at least in Canada you can vote for a socialist democrat and nobody goes into cardiac arrest.
Canada is more progressive than the US and has rational gun laws. With the Canadian dollar down our US retirement funds would go further -- especially if we convert them before the US$ goes south with the next bankster fiasco.
Enjoy