How many businesses have multiple locations in the United States and
how are they distributed? (how many owners own 2 locations, 3-5
locations, 5-10, etc.) 

A problem with this question is that you're asking two different
things.

Many businesses with a large number of locations (e.g. Subway, Mailbox
Etc..) are franchises, where most branches are independently owned and
operated.  So although a business may have hundreds of locations, each
of the hundreds of owners may have only or two locations.

Would you really want to know how many locations are owned by each
owner, or is the question asking how many branches under their name
(including franchises) each chain has?

The Census and the SBA use the word "establishment", see
http://www.census.gov/epcd/ec97brdg/def/ESTAB.HTM

The most logical source of your information would be the Small
Business Administration at http://www.sba.gov but the preprepared
reports seem to be mostly by employment size (or turnover), rather
than number of locations.

Rob

Good point, Rob, I should have been more precise.  When it comes to
franchisees, I'd like to 'look through' them and see the underlying
franchise owners, each of whom would count as a business.  So Subway
wouldn't count as one business with say, 10,000 locations, but rather
as several thousand businesses, each of which would have from 1 to X
locations.

I did look a little at the SBA data, and I was able to conclude that
there's somewhat more than 1 million establishments that are
apparently owned by companies that own other establishments.  But what
I really need is the distribution of that ownership, as I posted in my
original message.