Every year, millions of plastic bags are dumped in landfills or our oceans. Paper bags brought home from the store often end up being crumpled and tossed into the recycling bin. It's practically a cultural mandate that you carry a shopping bag wherever you go, and many stores will reward you for BYOB with a credit toward your overall purchase.
Keep in mind that the manufacturing of cotton and hemp totes has a fairly significant impact. Cotton cultivation uses a tremendous amount of water, and unless the crop is organic, farmers employ toxic herbicides. The production of polyester or polypropylene bags is only marginally better than that of plastic bags in terms of natural resources used [source: Treehugger]. However, there is one huge advantage when choosing to BYOB: Tote bags are reusable and with a little care will last for years.