Complex sentence: In what is now the Loop Community Area, on the southern banks of the Chicago River, near today's Michigan Avenue Bridge, the U.S. Army erected Fort Dearborn in 1803-the first settlement in the area sponsored by the United States.
Split into simpler sentences: In what is now the Loop Community Area, on the southern banks of the Chicago River, near today's Michigan Avenue Bridge, the U.S. Army erected Fort Dearborn in 1803. It was the first settlement in the area sponsored by the United States.