The days of the corner grocer are long gone. Walmart, Kroger and Target turned the produce aisle into just another offering at big box stores. Now they face an even bigger threat: Amazon is expanding its same-day grocery business.

Prime members in 1,000 cities and towns will be able to order perishables like "blueberries and milk" and "get them within hours," said The Associated Press . That number will expand to 2,300 municipalities by the end of the year. That is "one of the most significant grocery expansions" that Amazon has undertaken, the company said in a statement, one that puts "pressure on grocery delivery services" offered by existing grocery giants.

Amazon is "all but fist-fighting your local grocer," said Morning Brew . The company already accounts for 20% of the g

See Full Page