Why Interstate 90 Skipped Pierre, South Dakota and the Future of U.S. Highways

The design of the Interstate 90 (I-90) was a strategic undertaking to connect the eastern and western coasts of the United States, running from Boston, Massachusetts, to Seattle, Washington. The routing of I-90, along with other interstates, was influenced by a variety of factors, including geography, population centers, existing infrastructure, and economic considerations.

Geographical Influences on Route Design

One of the key drivers in the design of I-90 was the geographical landscape. For instance, the Black Hills region in South Dakota significantly influenced the path of the interstate. The layout of the terrain and the natural features played a crucial role in determining the most suitable areas for construction and maintenance. I-90 was routed to pass through these regions in a way that minimized environmental impact and logistical challenges.

Population Centers and Economic Hubs

When planning the route for I-90, the U.S. Bureau of Public Roads aimed to connect major population centers and economic hubs. While Pierre, the capital of South Dakota, is a significant city, it is relatively small in comparison to other metropolitan areas in the state. The interstate was rerouted to connect to larger cities, such as Rapid City and Sioux Falls, which have more substantial populations and economic activities. This decision facilitated better connectivity and efficient travel for residents and visitors in these larger cities.

Existing Infrastructure Alignment

An important aspect of the interstate design was the consideration of existing road networks. I-90 was aligned to utilize and enhance pre-existing highways, ensuring smooth transitions and efficient connectivity. By leveraging already established routes, the construction costs could be minimized, and the overall traffic flow optimized.

Economic Considerations in Route Planning

Economic factors also played a significant role in the routing decisions. Areas with high traffic volume, commercial activity, and tourism potential were prioritized to maximize the benefits of the interstate system. For I-90, routing it south of Pierre ensured that it passed through regions with greater economic significance, contributing to the overall economic development of the region.

The Future of U.S. Highways

The primary function of early U.S. highways was primarily military, but they soon shifted to commercial purposes. Modern-day highways like U.S. Highway 83, which connects to I-90, demonstrate how these routes evolve. Currently, U.S. Highway 83 spans 55 kilometers (33 miles) and is a four-lane divided highway with a 65 mph (105 kph) speed limit, making the journey quite easy and efficient. Along the route, towns are well-equipped with amenities, making travel convenient for both locals and tourists.

While no Interstate route is currently required for U.S. Highway 83, there is potential for future developments. A toll or free Interstate route could be added in the future, catering to the growing traffic and commerce needs. In the plains region, where people are accustomed to covering long distances, even a short 30-minute drive is seen as a non-event. This adaptability and future-proofing are crucial in the evolving landscape of U.S. highways.