When the train carrying President Harry Truman and 60 reporters on a 15-state whistle stop tour during the 1948 campaign stopped at Cheyenne, Wyo., the press hustled off and started walking hehind the presidential motorcade.

Suddenly Alice Dunnigan, the only woman and only black with the correspondents that day, was grabbed by a military officer who shoved her toward the bystanders. Even though she was wearing saucer-size identificiation, another reporter had to verify her association with the White House party.

Later on the trip, Dunnigan had her feet propped up in her compartment her typewriter on a food tray across her lap, when a knock sounded at the door.

"Truman poked his head in. I didn't know what to do. In those days the press had awe and respect for the President," Dunnigan, long retired from her job with the defunct Associated Negro Press, recalled the other day. "I tugged at my skirt. I couldn't find my shoes. I knew I should be standing up. But I couldn't move. And Truman said, very quietly, 'I heard you had a little trouble. Well if anything else happens, please let me know.'"

A nice ending to an unpleasat incident. For Alice Dunnigan getting the story out to the black newspapers wasn't always that easy. In the Eisenhower administration she was ignored at press conferences because her questions always concerned discrimination.

"I always felt a journalist should be a crusader. I went to every press conference with a loaded question," she said. "And if I got an answer or a no comment or nothing, I had a story."

Spotlighting conditions of blacks in the United States and elsewhere has been one of the traditional roles of its 150th anniversary this week. A Black Press Archives, that will be the first national repository for black newspapers will be dedicated this afternoon at Howard University. The establishment of the archives underscores the interaction the black press has maintained with key events in the black American experience.

"Negroes Are Coming North by the Thousands . . . Find Chance for Independence Here," a fist-size headline of the Chicago Defender announced 60 years ago.

With that solemn assurance from the black press, nearly two million blacks in the five years following World War I dropped the plows of sharecropping and rode North for better times. In that period, black newspapers, the vehicle that triggered the massive migration, became the Southern sheriff's ammunition for harassment. Subscribers were labeled troublemakers. In most towns papers had to be distributed secretly by train employees, such as Thurgood Marshall Sr., father of the Supreme Court Justice. Yet, despite the tremendous dangers, scores of black newspapers survived, not only as traditional communicators but as catalysts for changes in society.

"We wish to plead our cause. Too long have other spoken fo rus," the first editorial of Freedom's Journal published March 16, 1927, announced. It set the standard of reform that many of the 3,000 black papers that followed have set as a goal. Some have succeeded and others have failed.

Many of those papers are included in the new archives, a joint project of the University and the National Newspaper Publishers Assn. (NNPA), a 37-year-old organization of black executives that is meet here this week.

The archives, housed in Howard's Moorland-Spingarn Research Center, will include a gallery of distinguished newspaper publishers and the papers and memorabilia of journalists.

The first contributors to the archives are Metz T. P. Lochard and Ethel Payne, associate editors of the Chicago Daily Defender; Dunnigan, the first black woman accredited to the White House and former director of the Washington Bureau of the Associated Negro Press; P. L. Prattis, former editor of the Pittsburgh Courier; and George B. Murphy Jr., national representative of the Afro-American Newspapers.

Not only have thouse journalists been recorders of the news but often their own lives became the story. Like the forums they represented, they harangued, they chastized, they praised and they made mistakes, and they made history.

At the turn of the century Ida Barnett Wells, a part-owner and editor of a Memphis newspaper, complied statistics on lynching. Her offices were destroyed, she had to flee the city, but her reporting raised the consciousness about the crime of lynching, later effecting decisions in historic cases like that of the Scottsboro Boys.

During the Depression, Carly Murphy, the editor of the Afro-American, used his own money to revitalize the Baltimore NAACP and then filed a suit that eventually led to the admission of blacks to professional schools in Maryland. In Oklahoma, roscoe Dunjee, the influential editor of the Black Dispatch, brought about a similar law.

The Atlanta World doggedly reported on a rape case until the state passed a law that the prosecutor could not ask for the death penalty for rape. In 1957, Alex Wilson, a black editor, was severely beaten as he guarded the nine teen-ages who integrated the Little Rock (Ark.) Central High School.

The Pittsburgh Courier, one of the most widely read black newspapers of the century, raised the travel expenses of Jackie Robinson so he could get to Brooklyn and become the first black to play major league baseball.

But the black press has not always been a do-gooder. Some papers have been out-and-out scandal sheets, others have skipped the cause of general improvement for a selfish one. In many cases the papers are poorly edited and unembarrassed reprinters of press releases.

Stylistically the black papers of the 19th century differed little from the austere, gray style of the general prses. In an early issue of Freedom's Journal, the standard size sheet was an unbroken mass to type, including an eassay by Washington Irving and letters on fraternal meetings and weddings. Later, when the white press had passed its era of sensationalism, the black press held onto it. "Fanatic Bakes Boy in Oven," announced a Chicago Defender headline in 1921.

Whether the papers were good or bad, they developed a special intimacy with the readers. It was often a buoyant, over-the-back fence tone. One of the most memorable examples was the headline of the Afro-American newspapers after the 1964 Civil Rights Act was passed. It proclaimed in red letters, "East Anywhere."

In the last two decades the prestige and monopoly of the black press had dramatically waned. Its dominant story, the struggle for equal rights, became the main story for all the media in the 1960s. To add the perspective of personal experience, the white media raided its talent banks. Then, coupled with its historic financial woes, its coverage became largely lackadaisical.

Today the 200 black newspapers published in the United States, including four dailies, are still committed to its watchdog role. Whether they are adequate is a lingering question. In the mid-70s a vacuum of reportage on black condition exists that neither the white nor black press is filling. Yet both the critics and supporters of the black press feel that as long as racism continues to be a reality, the black press has a role.

In 1972 the top 100 advertising agencies, according to figures from the NNPA, spent $1.9 billion in newspaper advertising. Only $2.3 million was spent in black media, according to Carlton Goodlett, the president of NNPA.

That's only one example of the revenue drought that is keeping the black press from improving with the necessary modernization, expansion and recruitment. "We are a victim of economic racism," says Goodlett, the publisher of several papers in the San Francisco Bay area with a combined weekly circulation of 113,000. "We have organized two groups to be advertising representatives and attract new clients. The Congressional Black Caucus has put this issue on its legislative agenda. We are ignored though in recent years our advertising revenues have increased a minuscule amount. But in 1973-74 the federal government spend $70 million advertising the voluntary army program and not one penny was spent in the black press."

Despite all the problems, some stories of the black press today are stories of hope. "I don't see the black press dying," says Raymond Boone, 39, the editor of the Richmond, Va., edition of the Afro-American. His slug 'em spirit and his "recommitment" to black accountability to the weekly in the last 12 years has helped raise its income from ninth in the Afro-American chain to number two.

"We've done it basically by dealing with issues head on," says Boone, the first non-Murphy board member of the Murphy family corporation. He declines to discuss the revenues but the paper has a weekly circulation of approximately 14,000, almost half the black households of Richmond.

"We have suceeded by being a newspaper and keeping faith with our readership. Other papers are locked into the establishment but we are totally independent," says Boone.

Under Boone's direction the Afro has urged a boycott of the National Tobacco Festival by governmetn officials and multie national corporations, won a campaign against media advertisements that told the entire Richmond community "you're looking good," as unemployment figures rose, and has sent its one full-time white reporter to apply for an apartment after a black Vietnam veteran working for the paper was turned down.

Boone, who doesn't hesitate to print his editorials on the front page, feels black newspapers are at the edge of a resurgence. "TRhe need is great. Black people are involved in a war of ideas with whites and we are greatly unarmed because we don't own a significant number of radio stations and only have one television station. When your mind is controlled that's the worst kind of enslavement. The black press needs a recommitment to be a shield and exposer of racism."