Early U.S. infrastructure system

Major dams and bridges were built by the Works Progress Administration (WPA) during President Franklin Roosevelt’s New Deal in the 1930s and 1940s and have withstood decades. The American Interstate Highway System came into being during President Dwight Eisenhower’s term over 60 years ago. U.S. sewers were built several generations ago. As a result, the U.S. infrastructure system is old and beginning to rapidly deteriorate.
What three critical components of the U.S. infrastructure system should be addressed first? Support your position.
How often do you think critical components should be inspected for weaknesses and vulnerabilities? Explain your rationale.