The Invisible Line That Shaped South Dakota’s Future

Whether we want to admit it or not, there's a long and invisible line that has determined much of South Dakota's history. This line will also (likely) play a pivotal role in its future in the years to come.

Does this line really exist and what is this line all about? Well, it determines how much precipitation a region will receive (on average) every year. And the results are hard to argue.

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The 100th Meridian West Line

The 100th Meridian West Line runs through the states of North Dakota, South Dakota, Nebraska, Kansas, Oklahoma, and Texas. What does it mean? Well, essentially, everything east of the line (Iowa, Minnesota, Missouri) has more green in their environment, while everything west (Western South Dakota, Wyoming, Montana) has a more arid environment.

If you've ever traveled through the state of South Dakota, you've likely seen the effects of this line yourself. For example, the town of Chamberlain, South Dakota, lies just east of the 100th Meridian, as its longitude is at 99°. The state's capital of Pierre lies at 100.3538° W, placing it directly on the Meridian. The two biggest cities in the state are on opposite sides of the Meridian, as Sioux Falls is at 96.7313° W, while Rapid City lies at 103.2310° W.

But is there any validity to the 100th Meridian West rule that everything east of it is green and everything west is brown? Of course their are outliers, but it definitely appears to hold weight, as if you look at precipitation levels throughout the U.S., most towns that are west of the line have much less rainfall than towns east of the line.

This all changes once you get past the Rocky Mountains, as it is argued that the Rockies themselves are largely responsible for the weather patterns east and west of the line in the first place.

Story Sources: South Dakota Public Broadcasting Website, 100th Meridian Wikipedia Page