NoYouShmoopie wrote:
I have a column with US phone numbers (all numerical, 10 digits). I would
like to have the State name in a column right next to the phone number, and
the Time Zone in the next column to the right.

I have the master Area Code, State, Time Zone data in any format needed: one
long string, range, VBA constant...

The obvious solution is to write a VBA that uses the 3 left-most digits and
scans the master area-code table to find a match. The only problem is that my
list of phone numbers has several 10,000 numbers and scanning the master area
code again and again will take hours...

Any advanced idea anyone?

Don't scan it again and again...? Do it once when you set up the file, then do
it only for new numbers when you add them.

Occasionally you may need to rescan the whole file as area codes get reassigned,
but if you do that once a quarter or some such that's probably enough.

Bill