The US Interstate highway system is often considered one of the largest infrastructure projects in US history. Thanks to an email exchange with the US Dept of Transportation, we were able to get the raw investment dollars over 40 years. We adjusted for inflation using 2020 dollars to find that the total investment in current dollars is $549 billion!

Download the full spreadsheet here by clicking on the bottom right of the embedded Excel spreadsheet.

Code: m187 USHwyCosts math xbMath