Happy Birthday, Mr. President: Obama at 50

In honor of the President's 50th birthday, on Aug. 4, 2011, TIME looks back at 50 milestones in his life, from his days in Hawaii to his historic run for the White House to the highs and lows of his presidency

Obama Begins Teaching Law
The future President teaches a class at the University of Chicago Law School. He began what would become a 12-year tenure as a constitutional law professor in 1991.

Happy Birthday, Mr. President: Barack Obama at 50