Walter Lippmann, for more than half a century a towering figure of American journalism, is appearing on a new 6-cent regular issue in the Great Americans Series.

The stamp is being issued Sept. 19 in Minneapolis in a first-day-of-issue ceremony during the convention of the National Newspaper Association, which is celebrating its 100th anniversary.

Lippmann's powerful mind, penetrating insight and simple but shapely writing style made him one of the foremost journalists of his time.

The author of more than 20 books, he was most widely known for his syndicated column "Today and Tomorrow," which he began writing for the New York Herald Tribune in 1931 after eight years as an editorial writer and editor of the New York World.

The column brought him a special citation Pulitzer Prize in 1962. He gave up the column in 1967, although he contributed occasional pieces to Newsweek magazine until 1971. He died three years later at 85.

Born in New York City of prosperous parents, Lippmann traveled abroad even as a child and attended private school and then Harvard, where he graduated Phi Beta Kappa in three years.

Lippmann worked for a year for Lincoln Steffens, the foremost muckraker of his day, investigating Wall Street and for a publication called Everybody's Magazine. Beginning in 1914, he joined in founding The New Republic, interrupted his journalism to work in Washington on President Wilson's peace proposals, returned to the magazine for a spell and then joined the New York World.

Like all issues in the Great Americans Series, the new stamp is dominated by a portrait of its subject. The Lippmann picture is based on several likenesses of him at middle age. The identification runs upward along the left; the postal data is at lower right. The stamp has been produced in one color, orange, by intaglio.

The stamp comes in post office panes of 100. There is a one-digit plate number along with two other customary marginal inscriptions for the copyright and Mr. ZIP.

Collectors of first-day-of-issue cancellations have the customary 30-day grace period from the day of issue, so orders must be postmarked by Oct. 19.

Collectors affixing stamps on their envelopes, which must bear addresses, have to add an additional 16 cents' postage to the Lippmann stamp to meet the first-class rate. Orders should be sent to Customer Affixed Envelopes, Walter Lippmann Stamp, Postmaster, Minneapolis, Minn. 55401-9991.

Collectors preferring full processing by the Postal Serivce should send their addressed covers to Walter Lippmann Stamp, Postmaster, Minneapolis, Minn. 55401-9992. The Postal Service will affix one 10-cent Petition for Redress stamp and two 6-cent Lippmann stamps to fulfill the first-class rate. The cost is 22 cents for each envelope ordered. Personal checks are accepted; cash is not welcomed; payment by postage stamps is rejected.