Washington nostalgists (to invent a word) often remember the not- far-gone days when the capital had five fiercely competing local daily newspapers. Who remembers a sixth?

Think now! If you were walking down a street and looking in windows -- windows of barbershops, bars or variety stores -- between 1894 and 1956, you'd see it: the Bulletin.

The one-page "poster" newspaper had three editions a day Mondays through Saturdays distributed to up to 1,000 outlets. It carried general news from the United Press wires. But it featured sports, important especially in the prebroadcasting days when all baseball games, including those of the Washington Senators, were played in daytime.

The man most identified with the Bulletin was its publisher from 1915 onward, Henry Tait Rodier, who died in 1977 at the age of 92.

A printer by trade, he got his start as a media entrepreneur early in the century because the strait-laced management of the Evening Star refused to run the sports scoreboard in front of its building at 11th Street and Pennsylvania Avenue NW on Sundays. (In those days Woodward & Lothrop draped its display windows to avoid accusations that it conducted business on the Christian sabbath.)

Rodier persuaded The Washington Post to let him erect an unrestricted scoreboard, including advertising space, in front of its building three blocks up the Avenue. Profits from that and similar scoreboards in other cities provided the money for him to buy the Bulletin and its printing plant.

Rodier once recalled that the high (and low) point in his news career was Election Day in 1916 when, based on early fragmentary reports, he ran a headline proclaiming prematurely that Woodrow Wilson had been reelected president. Next morning, the regular papers on his doorstep reported Charles Evans Hughes in the lead. Rodier's heart sank. But he was able to repeat his original headline on that day's late edition. Triple Transit Tryst

A notice from the National Capital Area Transportation Federation reports that it will hold a "special triple meeting on mass transit funding" on June 26 in conjunction with two other prohighway groups. Ralph L. Stanley, head of the Urban Mass Transportation Administration, will -- we are told -- entertain such questions as "Do you want more highway-use taxes diverted to subsidize Metro?"

The meeting at the Chevy Chase Holiday Inn is easy to get to, the notice unashamedly assures its recipients: "Friendship Heights subway station two blocks -- Metro's Red Line." Executive Privilege

This message is no surprise: "The board of directors of the National Council of Elected County Executive have launched a program to actively promote the elected County Executive form of government. The board, at a recent meeting at Hilton Head, S.C., announced that they have established a speakers' bureau . . . . "

But some might find the local source of the message a bit exceptionable. It comes on the letterhead of "News from the Office of [Prince George's] County Executive Parris Glendening," and in an official envelope with county-paid postage.

Your tax dollars at work.