By the 1930s, flourmilling on the riverfront was in decline. The technologies to harness waterpower and grind grain that were perfected in Minneapolis in the 19th century gave way to new technologies in the 20th century. Power could now be produced by steam and electricity, allowing industries to relocate away from the falls, near new markets and population centers. Some of the old water-powered mills were converted but others closed.
Railroads were still active, but trains became less and less frequent. In 1948, 72 passenger trains crossed the Stone Arch Bridge each day, but by 1978, the daily total dropped to only four. By the 1950s, the Gateway was considered one of the worst skid rows in the country. Forced to take action, the city tore down 14 city blocks in an urban renewal effort.