You could have just converted the existing document to a 2-column layout.

That said, I don't know what you mean by "It produced a single column running down the left side of all the pages". Unless the source you copied from had only short lines terminated by line/paragraph breaks, one would expect the text to span the full width between the margins. There's a macro in the Cleaning up Text Pasted from Websites, E-mails, PDFs etc. 'Sticky' thread at the top of this forum (https://www.msofficeforums.com/word/...s-e-mails.html) for cleaning up such text.

__________________
Cheers,
Paul Edstein
[Fmr MS MVP - Word]

I thought I should be able to simply change the number of columns to 2, but that caused all the text to stay in the left column. I tried this several times. I also realized that I could have used simpler method, i.e. select and copy all the text with CTRL-x, then paste it back into the same document using the correct paste option.