Iowa Primary Highway System

Iowa Primary Highway System

The primary highway system makes up over 9,000 miles (14,000 km), a mere 8 percent of the U.S. state of Iowa's public road system. The Iowa Department of Transportation is responsible for the day-to-day maintenance of the primary highway system, which consists of Interstate Highways, United States Highways, and Iowa state highways. Currently, the longest primary highway is U.S. Route 30 at 332 miles (534 km). The shortest highway is Interstate 129 at 0.27 miles (0.43 km).

The 20th Century was a transformative time for vehicular transportation. In the early years of the century, roads were problematic at best – dusty dirt roads when dry and impassably muddy when wet. Over time, federal money was set aside and bonds were issued allowing the roads to be paved. The U.S. Highway and Interstate Highway Systems connected Iowa to the rest of the country and made national travel feasible. Periodically, new highway construction and changing driving habits have resulted in the obsolescence of local highways, to which the primary highway system has adapted. The former primary highways, turned over to counties and local jurisdictions, county highways, and farm-to-market roads make up the secondary highway system.

Early on, Iowa's registered routes were marked with hand-painted signs created by the group maintaining the highways. When the primary highway system was created, prisoners in Iowa's correctional system began making highway signs. Today, Iowa's highway markers are compliant with standards set forth in the Manual on Uniform Traffic Control Devices.