Early republic 1790-1850: Erie Canal
Invention and discovery 1850-1910: Brooklyn Bridge
Transcontinental Railroad
Hard times 1920-1940: Empire State Building
Golden Age 1950-1965: U.S. Interstate Highway System
Chesapeake Bay Bridge-Tunnel
Jefferson National Expansion Memorial Arch
Megaprojects 1990-present: Central Artery/Tunnel Project