Initiated by the Federal-Aid Highway Act of 1956 under President Dwight D. Eisenhower, the Interstate Highway System is widely considered one of the greatest public works projects in the first 250 years of United States history. For the heavy civil construction industry, it represented an unprecedented era of standardized road building, requiring all routes to be freeways with at least four lanes, controlled access, and no at-grade crossings.

“Our highways badly need modernization and expansion to accommodate today’s vastly increased motor traffic,” Eisenhower said when signing the legislation.

Seventy years later, that statement rings just as true.

Authorized at an initial $25 billion — equivalent to $300 billion today — for the construction of 41,000 miles over a 10-year period, the massive construction undertaking ultimately spanned 35 years and cost approximately $114 billion, or $937 billion in 2026 dollars.

Today, the sprawling network spans 48,890 miles and serves as the main arteries for much of the U.S., generating an estimated economic benefit of $65 billion annually considering fuel savings, road safety improvements, and congestion reduction, according to research by the Washington, D.C.-based nonprofit TRIP.

“The Interstate Highway System is one of the most significant infrastructure investments our nation has ever made,” said Paul Diederich of Industrial Builders Inc., and TRIP Board Member. “For seven decades, it has strengthened our economy by connecting manufacturers, contractors, suppliers, and communities while improving the safe and efficient movement of people and goods. As our transportation needs continue to evolve, preserving and modernizing this network will remain essential to sustaining economic growth and America’s long-term competitiveness.”

Celebrating its 70th birthday this year, the Interstate Highway System is showing severe signs of aging, presenting an immense challenge for heavy civil contractors, engineers, and those who support the industry. The U.S. Department of Transportation estimates a staggering $196 billion backlog in necessary improvements nationwide, which includes $58 billion needed for pavements, $65 billion for bridges, and $73 billion for system expansion and enhancements.

Looking at local numbers, maintaining current pavement conditions in South Dakota would require local governments to increase annual roadway investment by 46 percent, while making substantial improvements would require roughly doubling current investment.

In North Dakota, 44 percent of major locally and state-maintained urban roads are in poor condition, costing drivers an average of $410 annually in additional vehicle operating costs. Additionally, 46 percent of the state’s bridges were built in 1969 or earlier, highlighting the aging nature of the transportation system. Despite recent investment increases, the state continues to face significant long-term preservation needs as it works to maintain its extensive rural highway network.

In Wisconsin, the state’s transportation network carried 68.7 billion annual vehicle miles of travel in 2024, a 20 percent increase since 2000. Currently, 42 percent of all major locally and state-maintained roads in Wisconsin are in poor or mediocre condition. Driving on these rough roads costs the average Wisconsin driver $839 annually in additional vehicle operating costs. Furthermore, 7 percent of the state’s bridges are rated in poor or structurally deficient condition, and 27 percent were built in 1969 or earlier.

For contractors, modernizing the network will require “right-sizing” the system, adding necessary lane capacity to existing corridors, and comprehensively overhauling safety features to handle the influx of both passenger and commercial freight. Freight moved by trucks is expected to increase substantially by 2050, including a 53 percent increase by weight in Wisconsin alone.

“The Interstate Highway System is more than concrete and steel; it is a living symbol of American ambition, ingenuity, and unity,” TRIP Executive Director Dave Kearby said. “Built by a generation that believed in creating something bigger than themselves, these roads connected families, fueled commerce, strengthened national defense, and opened the country to endless opportunities. As we reflect on its 70th anniversary and America’s 250th, rebuilding this system is not just an investment in infrastructure; it is a chance to honor that legacy and ensure future generations inherit an America that still believes in building boldly for tomorrow.”

For more information and access to all TRIP reports, go to www.tripnet.org.

Lisa Mead is the Marketing and Partnership Director for TRIP, a national transportation research nonprofit.