This is a little more complicated than you might think.
Wikipedia gives the following list. I've broken it down into categories.
Definitely:
Canton, Ohio
Canton, California
Canton, Connecticut
Canton, Georgia
Canton, Illinois
Canton, Iowa
Canton, Kansas
Canton, Maine
Canton, Massachusetts
Canton, Michigan
Canton, Minnesota
Canton, Mississippi
Canton, Missouri
Canton, New Jersey
Canton, New York
Canton, North Carolina
Canton, Oklahoma
Canton, Pennsylvania
Canton, South Dakota
Canton, Texas
Canton, West Virginia
Canton, Wisconsin
Almost but not quite:
Canton City, North Dakota
Iffy:
Canton, Baltimore, Maryland, a neighborhood and park
Canton, Montana, a former town now situated under Canyon Ferry Lake
Canton, a village within the town of Canton, New York
Canton, Barron County, Wisconsin, an unincorporated community
There are also several townships (not quite the same thing as towns):
Canton Township, Fulton County, Illinois
Canton Township, Michigan
Canton Township, Fillmore County, Minnesota
Canton Township, Stark County, Ohio
Canton Township, Bradford County, Pennsylvania
Canton Township, Washington County, Pennsylvania
There are several cities named Canton in the United States, with the most notable ones located in Ohio, Michigan, and Massachusetts. Additionally, there are smaller towns and communities named Canton in other states like Connecticut and Texas. Overall, the number of places named Canton across the country can vary, but there are at least five prominent ones.
21
10
Five
1
None.
Is 1
There are many cities named Canton. The best known is in China (in Asia), but there's also a Canton, Ohio in North America.
The question should be: How many states have cities named after them in THEIR state? (If it is worded in this manner.) Or better yet: How many states also have a city with a matching name, such as Kansas City, Kansas?
23
5
1