Arizona, California, Connecticut, Delaware, Florida, Illinois, Maryland, Missouri, New Hampshire, New Jersey, New York, Ohio, Oklahoma, Pennsylvania, Rhode Island, South Carolina, Texas, Vermont, Virginia, Washington state, Wisconsin
Mitt Romney 11 states, 251 delegates
Alaska, Colorado, Maine, Massachusetts, Michigan, Minnesota, Montana, Nevada, North Dakota, Wyoming, Utah
1,191 delegates needed for nomination. Source: AP (includes all kinds of delegates)
Mr McCain also won in Illinois, Oklahoma, New Jersey, Missouri, Connecticut, Delaware, and his home state of Arizona.
Speaking in Phoenix on Wednesday, Mr McCain said: "The majority of Republicans across the board have stated their view so I hope that we can now join together for the good of the party and the good of the conservative cause."
The Democratic race was as tight as forecast, although Mrs Clinton secured the two biggest prizes.
In New York, her home state, she captured about 57% of votes to Mr Obama's 40%.
In California, with most precincts counted, Mrs Clinton had won 52% of Democratic votes and Mr Obama about 42%.
Mrs Clinton also took Arizona, Massachusetts and New Jersey, as well as the southern, rural states of Oklahoma, Tennessee and Arkansas.
However Mr Obama won a greater number of states, namely Alabama, Alaska, Colorado, Connecticut, Delaware, Georgia, Idaho, Kansas, Minnesota, Missouri, North Dakota, Utah and his home state of Illinois.
I think we must get used to the idea that we are the Republican Party front-runner