Watching “How the States Got Their Shapes,” the new History Channel show (9 p.m., Tuesdays), is sort of like sitting through an hourlong history class taught by a favorite teacher.

Larry talks with Mark Stein, author of "How the States Got Their Shapes," about the historical and geographical reasons our states' boundaries became the jigsaw puzzle we take for granted.

Object Details Author Stein, Mark 1951- Summary We are so familiar with the map of the United States that our state borders seem as much a part of nature as mountains and rivers. But every edge of the ...

The map of the United States is a jigsaw puzzle of crooked lines, right angles and odd shapes. Some pieces are outsized; others are minuscule. The reason for our jagged geography? American history.