Is it public domain or what?

From this thread several people offer out some great websites filled with hours of music recorded between the 1910-1930’s

Of course, like many in that thread, I’ve been going download crazy because this music is so cool.

Being a musician, I’ve been thinking today about perhaps re-doing a few of these tracks for a new CD.

How does one go about making sure these are in the public domain? I know I can hire the firm I’ve used in the past to clear tracks, but that costs a bit of money… money I’d rather not spend if there is a way to research myself.

Any pointers?

The rule is that anything published in the US prior to 1923 is in public domain.

Anything published 1923-1963 may or may not be PD, depending on whether the copyright was renewed.