The new sandwiches will be added to the menu of 180 test locations in Milwaukee, WI, Cedar Rapids, IA, Augusta, GA, Cincinnati, OH, and Buffalo, NY.
They include The Impossible Whopper Jr. - a smaller version of the Whopper, The Impossible Burger featuring ketchup, mustard, and pickles on a sesame seed bun and The Impossible Cheeseburger with all the above ingredients plus cheese.
The trial follows the national roll-out of Burger King's Impossible Whopper, which features the same burger build as the store's traditional beef-based option, replacing the beef with Impossible Foods' plant-based patty.
Ingredients include tomatoes, lettuce, mayonnaise, pickles, and sliced white onions on sesame seed bun. Mayo can be removed to make the option free of animal ingredients.
The sandwich initially launched in 59 stores around St. Louis in Missouri on April 1. Since then, it has rolled out to eateries in Missouri, Miami, Alabama, Georgia, and the San Francisco Bay Area.
According to sales data from market analysis firm inMarket Insights, stores that sold the sandwich saw a staggering 18.5 percent increase in foot traffic during the test.
"From the launch of our test in St. Louis, we knew that our guests really enjoyed the taste of the flame-grilled Impossible Whopper," said Chris Finazzo, president, North America, Burger King Corporation, in a statement earlier this year.
"We're now making the Impossible Whopper available for our guests across the country at an unbeatable price for a limited time only so visit one of our restaurants before they sell out."
'Plant-based not vegan'
While some vegans have embraced the burger, ordering it without mayo as an animal-free option, others have chosen to eschew it because of Impossible Foods' history of animal testing.
Impossible Foods itself describes its patty as plant-based rather than vegan because one of its ingredients - soy leghemoglobin aka 'heme' - was fed to rats in order to test its safety. In excess of 180 rats were killed as a result of the testing.
When the testing became public knowledge, Impossible Foods CEO Pat Brown, a vegan of more than 16 years, published a statement titled The Agonizing Dilemma of Animal Testing.
In it, Brown said the core of his company's mission is to 'eliminate exploitation of animals in the food system', as well as reduce the impact of animal agriculture on the environment.
"Among the thousands of animal species surveyed every decade by the World Wildlife Fund, the total number of living individual wild animals today is less than half what it was 40 years ago," he wrote.
"This wildlife loss is overwhelmingly due to the exploitation of animals for food, including hunting, fishing and especially the replacement of wildlife habitat by animal farming."