It has been generally credited as the world's first fast-food hamburger chain. It is known for its small, square hamburgers referred to as "sliders". It was founded on September 13, 1921.

The burgers were initially priced at five cents until 1929 and remained at 10 cents until 1949. In the 1940s, White Castle periodically ran promotional ads in local newspapers which contained coupons offering five burgers for ten cents, takeout only.

There are over 420 White Castle outlets, predominantly in the Midwest, Kentucky, and Tennessee. The exceptions are a significant smattering of outlets in the New York metropolitan region, three locations in Nevada, two in Arizona, and two in Shanghai. 

White Castle also markets its sandwiches in 30-hamburger boxes, called a Crave Case. The figure of 30 burgers represents the number that can be produced on one of its standard grills at the same time.  A "Crave Crate" is also offered, with the contents being 100 burgers. A variety of White Castle products (mostly frozen) are also sold in grocery stores.

Other events:

- 56th anniversary of establishment of National Society of Blackjacks (September 13, 1967 - September 13, 2023)

- 96th anniversary of establishment of Victor Company of Japan (September 13, 1927 - September 13, 2023)

According to en.wikipedia