Combine ground beef, onion, and garlic in large stockpot. Cook and stir over medium heat until beef is brown. Drain.
Stir in chili powder, salt, oregano, tomatoes, and tomato sauce; break up tomatoes while stirring. Heat to boiling, reduce heat to simmer, and cover. Cook, stirring occasionally, for 1 hour.
Stir in beans. Simmer, uncovered, for 20 minutes; stir occasionally.