How do I find the congressional record from 1921?

I’ve been reading up on the activities of the “second” KKK, which existed from the mid-1910’s until WWII. Apparently, their acts of vigilantism prompted a congressional investigation in 1921, which resulted in nothing but giving the Klan notoriety and increased membership.

My question is this: how can I track down documents relating to that 1921 congressional investigation? I’d like to know what prompted congress to investigate the Klan (who sponsored it), what was debated, and if / results of any votes.

The modern website only contains the congressional record back to 1995. How do I find records from 1921?

You can download a free copy in PDF format from the Government Publishing Office: