Part of the work of the League was to distribute campaign literature, and many of the radical pamphlets on reconstruction and the Negro problem bore the Union League imprint.

The New York League sent out about seventy thousand copies of various publications, while the Philadelphia League far surpassed this record, circulating within eight years four million five hundred thousand copies of 144 different pamphlets.

The literature consisted largely of accounts of "Southern outrages" taken from the reports of Bureau agents and similar sources.
With the close of the Civil War the League did not cease its active interest in things political.

It was one of the first organizations to declare for Negro suffrage and the disfranchisement of Confederates; it held steadily to this declaration during the four years following the war; and it continued as a sort of bureau in the radical Republican party for the purpose of controlling the Negro vote in the South.

Its representatives were found in the lobbies of Congress demanding extreme measures, endorsing the reconstruction policies of Congress, and condemning the course of the President.