What 19 states make up tornado alley?

There are not 19 states in Tornado Alley, though there is some variation in how the maps are drawn. Tornado Alley includes much of Texas, Oklahoma, Kansas, Nebraska, South Dakota, Iowa, and smaller portions of Colorado and Missouri. Some maps also include Arkansas, North Dakota, and Illinois but that is stretching it a bit. Louisiana, Mississippi, and Alabama are sometimes listed, but these are actually part of Dixie Alley.