Declaration of the Báb the evening before the 23rd: A merchant of Shiraz announces that he is a Prophet and founds a religious movement that would later be brutally crushed by the Persian government. He is considered to be a forerunner of the Bahá'í Faith; Bahá'ís celebrate the day as a holy day.
Samuel Morse sends the message "What hath God wrought" (a biblical quotation, Numbers 23:23) from the Old Supreme Court Chamber in the United States Capitol to his assistant, Alfred Vail, in Baltimore, Maryland, to inaugurate a commercial telegraph line between Baltimore and Washington D.C.
The Great Anticipation: Millerites, followers of William Miller, anticipate the end of the world in conjunction with the Second Advent of Christ. The following day became known as the Great Disappointment.