This completely depends on where you are camping--not only because local regulations will apply, but also because bears will have different behaviors and in some cases different species.

In the Sierra Nevada in California, bear canisters are required in all the national parks. Only a few backcountry campsites have bear boxes for use by hikers. And we are dealing with black nears there.

I would imagine that in Glacier it's a different scenario with the Grizzlies there.