What common leavening agent is used in most American waffle recipes?

What common leavening agent is used in most American waffle recipes? Baking powder is the usual answer.

American waffles are generally made from a pourable batter containing flour, eggs, milk or buttermilk, fat, and baking powder. The baking powder releases carbon dioxide when moistened and heated, creating bubbles that make the waffle lighter and less dense than an unleavened flatbread.

Baking soda is a common mix-up. It can appear in waffle recipes, especially those using acidic buttermilk, but it generally needs an acid to react properly. Yeast is also used in some traditional or overnight waffle batters, while cream of tartar is usually an ingredient in baking powder or a stabilizer for whipped egg whites rather than the primary leavening agent.

American waffles are typically thinner and denser than Belgian waffles. Their familiar round, square, or rectangular shapes and crisp-edged pockets make them especially suited to butter, maple syrup, fruit, fried chicken, and other toppings.