In time for the 40th anniversary of the March on Washington, the Library of America is publishing a landmark collection of civil rights reporting in America, Reporting Civil Rights. The two-volume work is at once a testament to our country's First Amendment rights, and a somber yet inspiring portrait of oppression. The editorial advisory board, which includes Clayborne Carson, David J. Garrow, Bill Kovach and Carol Posgrove, has chosen pieces that span from 1941, when blacks struggled for equal treatment in the Army, to 1973, when, writes Alice Walker, ""freedom [was] still an elusive tease, and in the very act of grabbing for it one [could] become shackled."" Among the treasures here are Langston Hughes's 1945 recollection of eating in dining cars south of the Mason-Dixon line; a 1963 piece by Hunter S. Thompson on Louisville, Ky. (""a Southern city with Northern problems""); and John Hersey's 1964 article from The Saturday Evening Post about a black man who tries to register to vote. There are nearly 200 newspaper and magazine reports, book excerpts and features in each volume. B&w photos.