Patriots' Day is not a postal holiday. The United States Postal Service (USPS), as an independent agency of the executive branch of the U.S. federal government, exclusively observes holidays established by federal law. Because Patriots' Day is a state-level civic holiday, recognized officially only in Massachusetts and Maine, it does not meet the criteria for a nationwide postal service closure.
The operational schedule for the USPS is dictated by a specific list of federal holidays. These include New Year's Day, Martin Luther King, Jr.'s Birthday, Presidents' Day, Memorial Day, Juneteenth, Independence Day, Labor Day, Columbus Day, Veterans Day, Thanksgiving Day, and Christmas Day. Patriots' Day, which commemorates the Battles of Lexington and Concord and is observed on the third Monday of April, is not on this federal list. Therefore, it does not affect the operations of federal entities.
As a practical matter, all USPS post offices maintain their normal operating hours and mail delivery proceeds without interruption on Patriots' Day throughout the entire country, including within the states of Massachusetts and Maine. While many state and local government offices, public schools, and some private businesses may be closed in those specific states, individuals and businesses can expect all postal services to be fully functional.
