Running a supermarket in America has never been harder. Profits are razor thin. Online shopping and home delivery are changing the way people buy their food.

Enter Aldi, a German discount grocer, which has gained popularity among budget-conscious shoppers in the United States ever since the Great Recession. Aldi’s latest expansion builds on that momentum. "Over the last 10 years, they’ve really flourished in the US,” said Mikey Vu, partner with Bain & Company. “There’s instability in the economy. People are worried. They’re paying much closer attention to pennies on their grocery purchases than ever before.”

Aldi scores higher on customer satisfaction surveys and benefits far more from word-of-mouth marketing than Walmart and other supermarkets. It has one of the highest Net Promoter Scores — a key measure of how likely customers are to recommend the brand to their friends and family — in the grocery industry, according to Bain & Company.