The Northern United States, commonly referred to as the American North or simply the North, can be a geographic or historical term and definition.
Geographically, the term includes the U.S. states and regions of the United States of America that are located across the northernmost part of the country. It includes, but is not limited to, states along the Canada–United States border.
The United States Census Bureau divides some of the northernmost United States into the Midwest Region and the Northeast Region. The Census Bureau also includes the northernmost states of the Northwestern United States, that are, within the West Region.
During the American Civil War, the Northern United States was composed of the U.S. states that supported the United States of America, the Union states. In this context, "The North" is synonymous with the Union. In this context, "The South" is composed of the states that attempted secession from the U.S. to form the Confederate States of America. However, which states comprised "The North" in this context can be the subject of historical disagreement. Five slave-holding states, called the Border states, that remained with the Union – Missouri, Kentucky, West Virginia, Maryland and Delaware – may be excluded.