Dear BigBas:

You. are. amazing!!!

That worked exactly as I needed it to (once I realized that I was using Mac Excel 2008.. which doesn't have VB Editor. Grrr). I realized that some normalization on my other spreadsheets was necessary, so I ended up having to adjust the numbering scheme to match the macro, since I couldn't figure out how to change it to match something that looks like this:

02_A-00456
02_Q-00103

(those were single-values in the A column, but there was an associated range in the B column)

So in the future, if I need to do that again, what bits would I look at changing to fit the data?

Thank you so, so, so much for saving my bacon. I ended up with approximately 150,000 rows across three spreadsheets, by the way.