Walk through the produce section of your supermarket and you'll see things you'd never have seen years ago — like fresh raspberries or green beans in the dead of winter.

Much of that produce comes from Mexico, and it's the result of the North American Free Trade Agreement — NAFTA — which took effect 20 years ago this month.

In the years since, NAFTA radically changed the way we get our fruits and vegetables. For starters, the volume of produce from Mexico to the U.S. has tripled since 1994.

Photo by Flickr user pantagrapher

U.S. and Mexican authorities today signed an agreement that will allow trucks from both countries to carry goods far beyond the border separating the two.