What letter do most US states begin with?

There is no one letter that "most" (more than half) of the U.S. states begin with. Perhaps you mean "With which letter do the most U.S. state names begin?" "The most" means more than any others.

That answer would be M, with 8 states:

Maine

Maryland

Massachusetts

Michigan

Minnesota

Mississippi

Missouri

Montana Even with the Norths and News, N is only second, with 7. # Nebraska # Nevada # New Hampshire # New Jersey # New Mexico # New York # North Carolina # North Dakota It would have to be both M and N since they both have 8 states between them.