There's no American condiment that's as beloved as ketchup. This thick, gloopy sauce is a staple at summer barbecues, where it's smothered on top of fresh-from-the-grill burgers or hot dogs.

There's nothing quite like a hot dog with ketchup slathered on the top of hot, crispy fries dipped in savory ketchup. Some version of this beloved condiment has been served alongside food since ...