There are 63,000 structurally deficient bridges in the United States.

http://www.dailykos.com/story/2014/04/24/1294382/-Scary-and-sad-There-are-63-000-structurally-deficient-bridges-in-the-U-S#

The expected cost to upgrade all of our bridges is about one trillion dollars.  While this is expensive, it won’t get any better by postponing repairs.  And if you are looking for funding, cut back on some of the multi-billion dollar defense bungles. 

Fixing our crumbling infrastructure would put a lot of Americans to work.  It would also increase the nation's security.

And it isn’t just our bridges that are vulnerable but also the nation’s electrical grid.  From a 2012 article in USA Today: 

http://www.usatoday.com/story/news/nation/2012/11/14/power-grid-vulnerable-terrorism/1704803/

“a long-delayed federal study Wednesday says the U.S. power grid is also vulnerable to terrorist attacks that could cause months of blackouts and billions in economic damages.”

This is because the grid is old, not secured, and without backup replacement parts.