Oct. 28—White Castle celebrated the recently completed expansion of the chain's food manufacturing facility in Vandalia on Thursday morning, with state and local officials recognizing the restaurant's $27 million investment.

Here's five things you need to know about White Castle:

1. 6 BILLION: White Castle's retail division sold its six billionth retail Slider hamburger at the end of 2021 and achieved record sales last year. To keep up with retail demand of frozen Sliders, White Castle broke ground last July on a major expansion of its Vandalia plant, which was completed in August. The expansion roughly doubles the plant's size from about 71,000 square feet to 145,000 square feet.

2. MORE JOBS: Company officials said Thursday that they've already expanded from 210 employees to 290 (including temps), and they're looking to hire 20-30 more people.

3. 530K SLIDERS A DAY: The expansion added two additional production lines to the facility, with one line still under construction and estimated to be up and running by the end of the year. This will increase the plant's manufacturing capacity from about 530,000 Sliders per day prior to the expansion to over 1 million once both new lines are fully functional. Production of the Sliders involves multiple points along the manufacturing line, beginning with cooking the patties and assembling the sandwiches, which then go through an expedited freezing process. The plant uses vertical spiral freezers to fully freeze the sandwiches in 90 minutes. The Sliders are then packaged and sent for shipping to grocery stores throughout Ohio and the nation. Located on 17 acres off U.S. 40 and Peters Pike, the Vandalia plant was designed to produce more than 16,000 hamburgers per hour per production line. The plant opened in late 2013, quickly hiring more than 100 employees in its early days.

4. KANSAS START: Billy Ingram opened White Castle in Wichita, Kansas, in 1921, selling the iconic little burgers the family-owned business has become famous for. So easy to eat, they were dubbed "Sliders" and sold by the sack. Ingram moved White Castle to Columbus in 1934 after buying out Walter Anderson's share.

5. BUY 'EM BY THE SACK: In 1927, Billy Ingram invented restaurant carryout and unveiled the new tagline, "Buy 'em by the sack." In 1947, White Castle modified its famous Slider, adding five holes to speed cooking and add flavor. In 1962, White Castle began serving cheese Sliders, the first new item to grace its menu since it opened in 1921.