Grocery delivery services have trouble keeping up during social distancing

Which apps have availability and which are booked for days

With hundreds of people lining up to get inside grocery stores and bans on gatherings of more than 50 people, what used to be a luxury is becoming a necessity: grocery delivery.

That is putting a strain on Amazon, Walmart and other retailers who in the past were able to deliver your supplies in a matter of hours. Now, you might have to wait days.

» Complete coverage: Coronavirus

Amazon said Tuesday it would now prioritize orders in the short term.

“We are making the decision to temporarily prioritize household staples, medical supplies and other high demand products coming into our fulfillment centers so we can more quickly receive, restock and ship these products to customers.”

If you've tried to order from Amazon Fresh recently, you know why. On Wednesday morning, delivery was unavailable through Friday, which is the latest date you can see.

A similar problem occurred when ordering from Walmart. As early as 9 a.m., all availability for Wednesday delivery was gone.

» Rules for buying during coronavirus pandemic

» Target, Dollar General, grocery chains offer 'elderly hours' for those vulnerable to coronavirus

Walmart spokeswoman Molly Blakeman told USA Today the company was trying to keep up with "unprecedented demand," that consumers should shop early and come back often. Her tip: Try ordering from different local Walmarts until they find a store that will fulfill the orders. "Keep checking back."

» Some store shelves quickly empty but experts say it's short term

The Target in Duluth, however, had several spots available, but many items could be delivered only via Shipt, which requires a membership.

The best option we came across Wednesday was Instacart, which works with 25,000 grocery stores. At 11 a.m., we could get groceries "within 5 hours." There were spots open for Thursday and Friday delivery. There is a $3.99 delivery fee. But its time slots go quickly, too.

"Based on the current surge in demand, customers can expect to see delivery availability vary across stores during the busiest request windows," Instacart said. "Delivery windows are specific to individual store volume and shopper availability. As availability opens up for an individual store, customers will see these delivery windows become available on the Instacart marketplace."

» Publix to close stores each day at 8 p.m. until further notice due to coronavirus