Convert stereo to mono?

I have a stereo wav file, in which both channels are identical. (The original source was mono.) Is there a way to save just one channel as a mono version of the file? Thank you.

There is a little drop-down arrow to the left of the waveform. Click Split Stereo To Mono. You’ll still see two waveforms but when you export they will be combined to mono.

Got it, and it works. Thank you!

@DVDdoug’s suggestion relies on a preference setting to “Mix Stereo Down to Mono on export” being set. There is also the “Tracks|Mix|Mix Stereo Down to Mono” menu item that does this operation explicitly.