The regular “unpaid” U.S. Dept of State Internship for Summer 2017 opened for application on September 1 and will close on October 14. Minimum requirements: U.S. citizen, 2.5 cumulative GPA or above, and must be returning to school after the internship is completed (students graduating this May can still apply if they plan on going to grad school or continuing school in any fashion---also, it is open to undergrad, grad, and postgrad students).
More details at: https://careers.state.gov/work/opportunities/vacancy-announcements/dos-student-internship-unpaid