Circulation figures for the largest "underground" press publications: Ulrich's Interational Periodicals Directory, 13th ed., 1969-70.
For this edition of Ulrich's, at p.786, under "Literary and Political Review," the circulation figure for Village Voice is 130,000, and it is 85,000 for LA Free Press. Ulrich's circulation figure appears to provide the only available information of its kind, whatever its deficiencies. There are also entries for Berkeley Barb and the Haight Ashbury Tribune, but they do not identify circulation figures.
(answer from mginsborg)