During the busy weeks before Christmas, several District Liners wrote to tell me they had difficulty in mailing large packages.

Their problem was that although small post offices will accept packages weighing up to 70 pounds the limit at large first-class post offices is 40 pounds. It seemed silly to readers that postal clerks should have to refuse them service on packages ranging between 40 and 70 pounds in weight - and then suggest on the sly that the package be taken to a smaller office, where it would be accepted. "Who makes such silly rules," one reader asked.

As we have learned in tracking down hundreds of life's little mysteries like this one, there is usually a reason for silly rules, or at least an explanation for how they came into being.

A bit of investigation in the present case turned up the fact that the weight limitation rule wasn't dreamed up by the U.S. Postal Service. It is a law passed by Congress (39 U.S.C. Sec. 3682).

As so often happens, private interest groups (spearheaded in this instance by REA Express) lobbied effectively to minimize the competition USPS would be permitted to give them Congress bought their argument and ruled that only small rural USPS officials could accept packages up to 70 pounds (because the private carriers didn't have offices in rural areas).

USPS has repeatedly asked Congress to change the rule and permit all post offices to accept the larger packages. In recent years, USPS has accompanied this request with a reminder that REA Express has long since gone out of business. But Congress, in its infinite wisdom, has chosen to take no action.

Unless President-elect Carter can get Congress to put this matter on its agenda for 1977, postal patrons will continue to wonder why the post office nearest them refuses some of their packages and thus makes it necessary for them to drive 10 or 15 miles to a small rural office.