Round cans simply do not store up very well en masse, and take up a lot more space in the garbage than their mass would dictate. They're made of very little material, but maintain a large hollow shape relative to that mass, and eat up more space than they have to.

A comparison could be made to balling up paper to throw it away. Left flat, the paper doesn't take up that much space and a lot can be stored.

The same ten sheets of paper that take up less than an inch high stack can make a foot tall pile if balled up and tossed away. Likewise, you can store twenty crushed cans in the same space as eight intact ones.

Enter the can crusher, a catch-all name for a series of devices designed to flatten the cans into more manageable shapes.

Crushers come in a variety of models, for a couple of ideas it is worth a look at www.can-crushers.biz, but the basic premise of all is to make crushing cans more efficient and remove the potential for injury almost entirely. Crushing cans has always been the most convenient solution, but does have it's drawbacks - primarily being inefficient and potentially dangerous. As mentioned, metal cans have the potential to be sharp. Crushing them by hand can lead to nasty gashes that, if the can wasn't cleaned, could get infected.

Even without this possibility the potential for injury alone should give people pause before they stomp their foot down as hard as possible on these things. This of course only addresses soda cans. *Soup* cans are much sturdier, and significantly harder to crush with human biology.