Walmart announced Wednesday that it will add dozens of 20,000 square-foot to 30,000 square-foot automated fulfillment centers in the coming years, either in the backrooms of its stores or next to them.

In the centers, robots will gather thousands of pantry items and frozen foods instead of employees, which Walmart says speeds up the process. The items will then be brought to an area where Walmart workers can assemble them into orders for pickup or delivery.

The centers may also ease traffic in store aisles because they will limit the number of Walmart employees gathering inventory directly from the store floor to fulfill online orders. Crowded aisles are a growing problem for stores as online shopping accelerates, and retail analysts have said these automated fulfillment centers help solve this challenge.