Many popular National Parks and Wilderness areas require a bear canister in the backcountry. Check local regulations online or call the nearest forest ranger station.
If you are in bear country, bear canisters are a good idea even if not required by law. Hanging your food correctly is time-consuming and often not possible. For instance, much of the mountain west is full of pine trees with very few suitable for hanging food. And in the desert west trees are sometimes non-existent.
Using a Bear Canister
With bear canisters, after dinner just walk the canister 200 feet or more away from your campsite. Be sure to put all items that smell in your bear canister including deodorant, lotions, and toothpaste. Finally, you might be wondering how many bear canisters you need? Generally speaking, one is enough for two people on a three-day backpacking trip. Check out our website for renting bear canisters and carry cases.
Some, or in certain areas many, campgrounds and alpine campsites have permanent bear boxes to store your food in (does not apply to backpacking). If so, you will not need a bear canister.
We always use carry cases for our bear canisters. A carry case allows you to lash the canister to the outside of your pack. Consequently, figuring out how to jam it into your already full pack isn’t necessary :).