[Libraries are closed for both Thanksgiving, Thursday, and also the shopping holiday, Friday, the day after Thanksgiving. I probably won't be on line those days.]

Used to be Thanksgiving in the US was the last Thursday in November. Now it's the fourth Thursday in November, which is often the last. But not always.

At the beginning of FDR's first time when the economy was flat on his back, his idea was try anything, especially easy stuff to start the engines. Thanksgiving as the last Thursday was quite late so he made it be the fourth Thursday to extend the Christmas shopping season.

Some people who didn't like change or didn't like him called that the Roosevelt Thanksgiving and observed the other one instead. So with things quite bad all around, there were two days of thanksgiving--couldn't hurt.