The University of Wisconsin Digital Collections has recently digitized additional volumes of the Foreign Relations of the United States. It now covers 311 volumes from 1861 to 1958/1960.
The Foreign Relations of the United States series is the official documentary historical record of major U.S. foreign policy decisions that have been declassified and edited for publication. The series is produced by the State Department’s Office of the Historian and printed volumes are available from the Government Printing Office.