Americans use 100 BILLION plastic single-use grocery bags each year. That's about 12 MILLION plastic bags in ONE HOUR.
One reusable bag can replace about 1,000 grocery bags in its lifetime. If you haven't yet made the switch to reusable bags, here is where you start.
One might be tempted to switch to paper bags, since, well, it isn't plastic, but that is a whole other environmental nasty ballgame in itself. Never mind the trees that are used to make the bags, the energy and other resources needed to make them are just as evil, including cleaning and preparing the bags using more chemicals.
If you are squeamish about starting to accumulate reusable bags, consider that they pay for themselves in no time, as most grocers offer bag refunds whenever you use them.
If you keep forgetting to bring your bags, make a pact with yourself that if you forget them you will have to do without bags for the trip - no taking plastic or paper because you messed up. It won't take more than a few times of your thoughtlessness to ensure that you will remember. Emptying your cart of goods into your car and then carrying them into your home will be just annoying enough that you will remember to bring your bags.
Most grocery stores now sell reusable bags made of plastic bottles (down-cycled) so you can start there, but consider buying your bags from companies that will take them back once they break or are no longer needed, to ensure that there is a positive end-life to your plastic. Or go with canvas bags.
And, mind you, the numbers above do not include other single-use plastic bags, such as produce, bread or the other tons of other stuff that are packaged in plastic bags and then tossed.
Get grocery tote bags from your grocer or try:
Reuse It - they also sell reusable produce bags.
Chico Bags - they also sell reusable produce bags.