Pub. L. 86-682, tit. 39, pt. I, ch. 7, sec. 707
Hours of service
§ 707. Hours of service (a) The Postmaster General shall require at least one person to be on duty at each post office during such hours of each day as he directs, to perform the functions of the office. (b) Post offices of the first and second classes shall not be open on Sundays for the purpose of delivering mail, other than special delivery mail.