Michael's quite right, hostels can be found all over North America, though they can be far between in more remote areas. Hostelz.com is probably the most comprehensive hostel listing (worldwide) on the internet, and they have thousands of listings for the US and Canada. Some you'd rather not go near, others almost the height of luxury. Hostels vary greatly, and in North America are quite different from the European hostels.

My first two trips in North America I hostel hopped all over, coast to coast, border to border, and criss-crossing the country every which way. And even though it is pay per person, at a good hostel the 'hostel experience' is worth it everytime. A good hostel is much more than a cheap(er) bed for the night.

On occasions, I still seek them out.

Lifey