Allison Farley, age 13, of Annapolis, Md., for her question:

HOW WAS THE MASON DIXON LINE NAMED?

Mason Dixon line was the popular name for the boundary line between Maryland and Pennsylvania, so called because it was surveyed in 1765 by two astronomers named Charles Mason and Jeremiah Dixon. This survey was undertaken in order to settle a dispute between the Calvert family, proprietors of Maryland, and the Penn family, proprietors of Pennsylvania.

Later the term Mason Dixon Line meant not only the old disputed boundary line but also the line of the Ohio River from the Pennsylvania boundary to its mouth, where it flows into the Mississippi River, then the east, north and west boundaries of Missouri, and from that point westward along the 36 degree 30 parellel.

The term Mason Dixon Line is still used sometimes today when we mean the boundary between the North and South.