I would agree that regional U.S. differences exist, but it transcends business to many other organizations, environment, and culture. The northeastern U.S. from Boston to Philadelphia is legendary for aggressive individuals and expectations in business, politics...even religion. Sports fans also reflect such attitudes in different U.S. cities from region to region. The midwest has a focused but more passive reputation, while west coast attitudes can seem flakey and narcissistic at times.
In the U.S. military, there is a marked difference in organizational attitudes from east coast to the west coast/Hawaii/Alaska, which some say if reflective of the distance from Washington, D.C. Years ago, I found military commands on the west coast to be far more lax than in the east.
Even hip-hop has its legendary east vs. west coast battles (Biggie vs. Tupac). The U.S. south has come into its own as population shifts favour relocations there.
My experience with Canadians in business (mostly IT) is that they were usually competent, but most disliked conflict and the blunt directness of Americans. This is a common refrain for many other nationals when dealing with Americans, reinforced by popular media.