The United States and Italy, in a joint issue, have just put out commemorative postal cards in honor of Francis Vigo, an Italian American who provided money and means to help George Rogers Clark defeat the British on the western frontier during the American Revolution.

The joint issue is one of several that the United States is planning this year. There has already been a joint issue with Sweden in honor of stamp collecting and international stamp shows. Coming up on July 4 is a joint issue with France to mark the centennial of the dedication of the Statue of Liberty.

Meanwhile, the Postal Service has announced a number of additional 1986 issues: four commemoratives honoring Navaho art; a 17-cent "Great Americans" regular issue for Belva Ann Lockwood, the first woman admitted to practice law before the Supreme Court and the National Equal Rights Party's presidential candidate in 1884 and 1888; and a 14-cent postal card saluting the National Guard. The U.S. card for Vigo was issued at Vincennes, Ind., which is now on the site where Clark gained his victory. was dedicated in a first-day ceremony in Rome.

The common design depicts Vigo in the foreground, and behind him Clark, leading his force of fewer than 200 men as they slosh through the icy, waist-high waters of the Wabash River.

In addition to the identification, a panel at the bottom bears the year "1779," the year when Fort Sackville, guarding Vincennes and the key British post in the area, fell to the Americans. The panel in the Italian version has "Francesco Vigo" and "1747-1836," the years of his birth and death. The postal information in both is at the top. The design is the work of David Blossom of Weston, Conn.

The card has been produced by offset in yellow, magenta, cyan and black by the Government Printing Office.

Collectors of first-day-of-issue cancellations have the customary 30-day grace period from the day of issue, which was yesterday, to place their orders, and the usual alternative ways of ordering.

Collectors acquiring the cards themselves should mail them for first-day cancellations to Customer-Provided Stationery, Postmaster, Vincennes, Ind. 47591-9991. The Italian version of the card is not available at U.S. post offices but is available in uncanceled or canceled form from the Philatelic Sales Division, Washington, D.C. 20265-9992.

Collectors preferring cards provided by the Postal Service should send their orders to Francis Vigo Postal Card, Postmaster, Vincennes, Ind. 47591-9992. The cost is 14 cents for each American card and 29 cents for each Italian card. Orders should indicate whether "mint" or "canceled" cards are desired. Personal checks are accepted, cash is not welcomed, and postage stamps are unacceptable in payment.