The Department of Agriculture warned egg prices may increase more than 20% this year, after December saw a year-over-year increase of 36.8%.

The ongoing egg shortage has prompted several major retailers to limit the amount of eggs that customers may purchase. At Costco and Whole Foods, shoppers are allowed a maximum of three cartons per customer. In contrast, Trader's Joe's limit is only one dozen per customer, per Business Insider.

Pittsburgh-area supermarkets are limiting egg purchases as soaring bird flu cases strain the nation's egg supply. Why it matters: The highly pathogenic avian influenza, also known as bird flu, has affected at least 23 million birds nationally in the last 30 days,