The Impossible Whopper will be available at all 7,200 U.S. locations by the end of 2019.

Thanks to the success of its trial in St. Louis, Burger King will add the Impossible Whopper, a plant-based alternative to the classic Whopper, to all 7,200 of its U.S. restaurants by the end of 2019.

The 59-restaurant test run in St. Louis, which was launched in early April, is “going exceedingly well, surpassing the most bullish expectations,” said a representative for Impossible Foods.

The nationwide launch will represent the largest meat-free fast-food experiment in the country. According to the Washington Post, the closest in size is Carl’s Jr., which is selling its Beyond Famous Star, made with Beyond Beef, at more than 1,000 restaurants.

California-based Impossible Foods makes plant-based products that taste like meat, dairy and fish. The company’s mission is to make the global food system sustainable by eliminating the need to make food from animals.

In 2016, the company launched its first product: the Impossible Burger, which uses “a small fraction of the land, water and energy used to make meat from a cow.”

About one in five U.S. consumers has reduced their red meat consumption in the past year, according to market research firm Mintel. And nearly two in five consumers say they’re trying to add more plant-based foods into their diet.

To promote the offer, Burger King surprised customers by serving the Impossible Whopper instead of the classic Whopper and filmed their reactions in a taste-test video on YouTube.

CSD Daily, Foodservice, Industry News