Why the 38th parallel?

Following a straight line in almost any direction around the globe begins to focus the opportunities for comparisons and connections. Holding to a specific latitude controls for even more variables, which should give deeper meaning to contrasts and similarities.
Why 38°N, specifically? Few other latitudes, north or south, pass through so many states and nations. This is a temperate, middle latitude that has proven conducive to human success. Because of its population concentrations, the Robinson map projection system, now widely used for world maps (adopted by the National Geographic Society in 1988), chose 38 degrees north and 38 degrees south as “standard parallels”--the two lines across the map where size and shape are depicted most accurately (while distortions occur at all other latitudes on maps).
The mean population center of the United States, today, falls near the 38°N latitude. This rather odd statistic identifies the “balance point” where an equal mass of people is found in all directions inside the 48 states. Though this point has gradually been shifting southward and westward, for the last few decades it has stayed very near the 38° line. The 2000 Census located it near Edgar Springs, Missouri, at 37°42’N, 91°48’W. Another way to locate the “center” of the continental United States was used by the author of PrairyErth, William Least Heat-Moon, who wrote about the Kansas county found by diagonal lines drawn between New York City and San Diego and between Seattle and Miami—an intersection that also marks 38°N. There, after decades of debates, a small remnant of the prairie ecosystem was recently protected as the Tallgrass Prairie National Preserve.
One answer to this question is simply that our starting point--our home--is on the 38°N line. While other latitudes must certainly offer meaningful insights, it has been delightful to realize that “our” line coincides with so many intriguing environmental and cultural stories. Without venturing more than a half-degree to either side of the 38th parallel, a long list of historical and cultural sites can be encountered. The fact that this zone--between 37°30’N and 38°30’—can be so tight will make the encounters even more intriguing. Perhaps sharing them will spark others to similarly explore “their” latitude lines.
Our over-arching theme deals with water: wetlands conservation, pollution, domestic supplies, and international tensions. Because 38°N is a middle latitude lying between extremes of climate found farther north and south, successful agriculture there has depended on irrigation canals and reservoir storage. Now, at this point in human history, environmental challenges associated with altered natural water systems are ubiquitous. How those pressures are being dealt with around the world may be the most valuable contrasts and similarities we can uncover by exploring 38°N.