Turns out, until 2003, most cars used a small switch made with a gram of mercury to light up under the hood and the trunk. Of course, there are mercury-free alternatives, and in Oregon, 116 auto shops participate in a free program to replace the switches with a switch that contains a steel roller. Shops in Idaho will also remove the mercury switch and safely recycle it. If you live in one of these two states, click here to find a local mechanic who will perform the surgery.
The Statesman article mentions a related issue that parents should know about: those little flashing lights in kids' shoes contain mercury.
[Source: Statesman Journal, Hat Tip to Joel A. Photo Credit: Statesman Journal]