Ten years ago (2007) there was a big rush to get Passports because rules were changed to require them to go to Canada. This year those passports are expiring. I would recommend doing it soon if you plan on traveling this year due to an anticipated rush.
https://travel.state.gov/content/passports/en/passports.html
http://travel.usnews.com/features/what-you-need-to-know-about-upcoming-passport-changes/
https://travel.state.gov/content/passports/en/passports.html
http://travel.usnews.com/features/what-you-need-to-know-about-upcoming-passport-changes/