Also curious that the Suez canal is wider than the Panama?
The US government has been improving ports since its early days. In fact, the expenditure of federal funds on "internal improvements" such as port improvements was quite the contentious issue in the early republic. But most of the world's trade moves by sea, and the US is and always has been a maritime nation. The ROI for port improvements is laughably high, so it has always been a no-brainer.
Panama is working on a new set of locks and other expansions (http://en.m.wikipedia.org/wiki/Panama_Canal_expansion_projec...) that will allow for post-Panamax ships.
Triple Es are 400m long and 59m wide, though their draft fits hair-tight (14.5m)