While it is common for students to take both the SAT and ACT, historically the SAT has been the test of choice on both the East and West Coasts while the ACT has been favored in the Midwest.
Because the tests have different formats, they may highlight different strengths of the student. Some students choose to take both tests to determine which better suits their particular strengths.
Research show in an August, 2013 article in The New York Times showed that the geographic pattern still holds.
SAT State Popularity Map
ACT State Popularity Map
