The only two states that were annexed are Texas and Hawaii. Most other territory of today's states was purchased although some of it was ceded to the US, partic

The only two states that were annexed are Texas and Hawaii. Most other territory of today's states was purchased although some of it was ceded to the US, particularly much of the Southwest was ceded to the US by Mexico as a result of the Mexican-American war of the 1840s. (This doesn't include Puerto Rico and a number of unincorporated territories which were a mix of annexed and purchased.)