The land speculators measured off a square mile and designated the six blocks in the center as a business section. Committees were appointed to recruit prospective merchants and their families to locate in the settlement. Such merchants soon began selling supplies to miners and pioneers. The city's location on the edge of the Plains and Hills and its large river valley made it a natural hub for the railroads that were constructed in the late 1880s from both the south and east. By 1900, Rapid City had survived a boom and bust and was developing as an important regional trade center for the Upper Midwest.