September 18 Holidays

National Cheeseburger Day celebrates the American invention of placing a slice of cheese on a beef patty — attributed to Lionel Sternberger of Pasadena, California, who added cheese to a sandwich at the Rite Spot Restaurant in 1926, though at least four other claimants contest the origin. International Equal Pay Day was established to raise awareness for the global gender pay gap — in the United States, women earn a median of $0.82 for every dollar earned by men, a gap that widens significantly for women of color. National Concussion Awareness Day raises awareness for traumatic brain injuries — an estimated 3.8 million sports-related concussions occur in the U.S. annually, many unreported because players fear being benched. Chiropractic Founders Day marks September 18, 1895, when Daniel David Palmer performed the first chiropractic adjustment in Davenport, Iowa, repositioning a deaf janitor’s displaced vertebra and reportedly restoring his hearing.