Complex sentence: Lake Itasca is a small glacial lake, approximately 1.8 square miles (4.7 square km) in area, in the Lake District of northwestern Minnesota, regarded as the source of the Mississippi River.
Split into simpler sentences: Lake Itasca is a small glacial lake, approximately 1.8 square miles (4.7 square km) in area, in the Lake District of northwestern Minnesota. It is regarded as the source of the Mississippi River.