WASHINGTON--In his State of the Union address, President Obama is calling on every state to require students to stay in high school until they graduate or reach 18.

Some 20 states already have that requirement; Illinois does not.

Illinois requires students to stay in school until the age of 17. That was increased from 16 years old in 2005.

Obama is making the proposal because stronger anti-dropout laws keeps students in school longer--thus increasing their lifetime earning potential.