MIAMI -- Some supermarkets in Florida are putting the brakes on cartnapping by using an electrical gizmo that stops the rolling baskets in their tracks.

Nationally, a grocery cart vanishes every 90 seconds, according to industry estimates. At $100 a cart, the thefts cost the supermarket industry millions of dollars a year.

Carts frequently end up as suitcases for vagabonds, go-carts for kids, cookout grills for beachgoers or artificial reefs in lakes and canals.

The new anti-theft contraption uses an underground cable surrounding the perimeter of a supermarket's property. When a cart comes within two feet of the boundary, a sensor triggers the right front wheel to lock. Only a special gadget can release the hold on the wheel.