Retailers and shippers are on a mad pre-holiday hiring spree, making them one of the few industries adding jobs during COVID-19.Why it matters: With the entire country turning to online shopping, shippers across the U.S. are preparing for unprecedented package volumes — around 80 million per day between Thanksgiving and Christmas — and frustrating delays.FedEx and UPS are hiring a combined 170,000 workers, reports the AP. DHL is adding 2,300.Amazon and Walmart have hired several hundred thousand since March.Between the lines: This should finally erase any distinctions between Black Friday and Cyber Monday.Retailers are also quickly building out warehouses and adding alternatives to delivery.Amazon has announced the addition of seven new warehouses in just the last month, notes Recode's Jason Del Rey. Walmart is adding pop-up warehouses.Kohl's and Target have doubled parking spaces for customers taking advantage of curbside pickup, per AP.The bottom line: 7 million packages could experience delays per day between Thanksgiving and Christmas, the president of ShipMatrix, Satish Jindel, tells the AP.