What flat area is in the middle of the United states and runs from the U.S into Canada?

The flat area in the middle of the United States that extends into Canada is known as the Great Plains. This region is characterized by its expansive grasslands and relatively flat terrain, stretching from Texas in the south up through the central U.S. and into Canada. It plays a crucial role in agriculture, particularly for wheat and cattle farming. The Great Plains are also known for their diverse ecosystems and significant cultural history.