What happens to used gift cards?

I was at Lowe's today. Surprise. I had to make a few returns. I had some items which had the original receipt. I had some items that didn't have the original receipt. It's Lowe's policy (as it is many retailers) to give store credit if you don't have the receipt. I don't have a problem with this policy. I had a few items to purchase anyway (2nd surprise). At the self-service checkout, the scanner wasn't cooperating (3rd surpise), so the friendly clerk scanned my items. I presented my store credit card that I had received less than 30 minutes prior (you know, a credit card sized, non-recycled piece of plastic) and paid the balance with my debit card. As the friendly clerk placed the now used piece of plastic in the special vinyl pouch under the cash drawer, I asked: "Lowe's recycles these cards, don't they?" I knew they answer, but I just had to ask.

"No they don't, I'm afraid to say". As if her apology would soften the bad news...

So, my task tonight is to find out how many plastic store "credit" cards are being added to the landfills daily...