Nature not only "abhors a vacuum," she isn't very fond of straight lines, either. There is one thing you can tell about the long, straight lines you see on the ground from an airline seat 30,000 feet in the air, and that is that they are evidence of a human hand at work. They may be roads, or railroad tracks, or the edges of a farmer's field, but they are not creeks, or the edges of a glacier, or anything else whose shape has been left to nature alone.
The "unnatural" or artificial character of long, straight lines came to mind this week because Saturday, Nov. 2, is the anniversary of the day in 1889 when both North Dakota and South Dakota became states. President Benjamin Harrison considered the two states to be "twins," so he shuffled the admission documents and covered their names while signing, thus ensuring that no one would ever know which state was officially admitted to the Union first and which second.The two states aren't really "twins" (South Dakota is slightly larger in area), but the border between them was established to make them as similar as possible. That border is a long, straight line - invisible from the air, invisible even on the ground - but it is precise and accepted by everyone just the same.
This long, straight line is a portion of the 46th parallel, the imaginary line that circles the earth 46 degrees north of the equator. Congress chose this line for the border because it ran right through the middle of what was then the Dakota Territory, and they knew it was the middle because the territory's northern and southern borders were also lines of latitude (the 49th parallel is our border with Canada, and the 43rd parallel is the northern border of Nebraska).
Do your children realize that almost all the straight lines they see as state borders on a map are really lines of longitude and latitude? There are a few that are angled (South Carolina, Georgia, Nevada, for example), but the vast majority of all these long, straight lines point exactly east and west or exactly north and south.
By understanding this fact, children can use state maps and national maps and even a globe of the Earth to make geographic comparisons of various points in the United States and around the world. Look at the western United States, for example. The northern border of California is the 42nd parallel, which is also the northern border of Nevada and Utah. (The line looks slightly curved on the map because of the distortion that occurs when we try to portray curved surfaces on flat maps.) But if you follow this line due east, you will discover that the 42nd parallel is also the northern border of Pennsylvania.
The point known as the "Four Corners," where the borders of Utah, Colorado, Arizona and New Mexico meet, is on the 37th parallel and is actually just north (1/2 degree or 35 miles) of the northern borders of Tennessee and North Carolina.
The way to discover these comparisons and to see how the long, straight portions of your state's borders were chosen, is to acquire that essential but inexpensive home learning reference known as a "road atlas." Rand McNally's paperbound version (about $8) includes longitude and latitude marks along the edge of each map, but my advice is to keep another learning aid close at hand: a magnifying glass.- Dr. William F. Russell's books for parents and children include "Classics to Read Aloud to Your Children" and "Classic Myths to Read Aloud." Send your questions and comments to him at Family Learning, 2400 E. Main Street, Suite 266, St. Charles, IL 60174-2414.