Originally Hwy 121, connecting Crofton to Yankton and Wausa, was a main north and south artery and was part of the Meridian Hwy that connected Canada to Mexico.
The Meridian Highway is built along the 6th Prime Meridian. After the completion of the Meridian Bridge in October 1924, Hwy 81 became the major north and south highway. This loss of highway traffic was a detriment to the local commerce.
Even though Main Street is not the main business district now, originally it ran this way to connect to the main highway.