Simplify the following text for a Grade 9 native English-speaking person.
Original: The Upper Midwest is a region of the United States with no agreed-upon boundaries , but it almost always lies within the U.S. Census Bureau 's Midwest region , which includes the states of Minnesota , Wisconsin , Michigan , Illinois , and Indiana .
Simplified: The Upper Midwest is a region in the northern portion of the U.S. Census Bureau 's Midwestern United States . Although there are no uniformly agreed-upon boundaries , the region is most commonly used to refer to the states of Minnesota , Wisconsin , and Michigan .