Which western movie am I thinking of?

I saw a western movie maybe 15 years ago and it's been bugging me ever since that I can't see it again because I can barely remember it. Can any western movie fans help me?

What I remember is that the industrialised world is moving in, and at one point a whole gang of main characters go stand in front of a train manage to hold it back with musclepower.

The single other thing I remember is when they're sitting around a camp fire and one of the older guys asks a boy: "How old are you boy?" The boy answers a year, for example 15, and the old guy replies. "Well, you better shut up if you want to live to 16". Or something like that, the quote isn't word for word...

So let's see what imdb's western movie fans can make of this ;)