National Eat a Hoagie Day is observed in the United States every September 14, celebrating the popular sandwich known as the hoagie, particularly associated with the Philadelphia area. The origin of the holiday is unclear, but it is believed to have ties to the submarine sandwich, which is commonly referred to as a sub. The term "hoagie" is prevalent in Philadelphia and Western Pennsylvania, with various theories regarding its name, including connections to Italian shipyard workers during World War I and street vendors in the early 20th century. To celebrate, people are encouraged to enjoy a hoagie from their favorite sub shop or make one at home, often sharing photos on social media with the hashtag #NationalEatAHoagieDay. The hoagie was declared the official sandwich of Philadelphia in 1992 by then-Mayor Ed Rendell, highlighting its cultural significance in the region.