1877 (MDCCCLXXVII) was a common year starting on Monday of the Gregorian calendar and a common year starting on Saturday of the Julian calendar, the 1877th year of the Common Era (CE) and Anno Domini (AD) designations, the 877th year of the 2nd millennium, the 77th year of the 19th century, and the 8th year of the 1870s decade. As of the start of 1877, the Gregorian calendar was 12 days ahead of the Julian calendar, which remained in localized use until 1923.