public domain, see below
Crop of page 239 of the 1959 Pitt student yearbook, the Owl. This work was originally published before 1964 had to have the copyright renewed sometime in the 28th year. If the copyright was not renewed the work is in the public domain. Renewals for copyrights from 1951 onward (and some, but not all, renewals for 1950 copyrights), as well as original registrations from 1978 onward are available online from the Copyright Office's Copyright Records web site.
Originally this issue of The Owl was seemingly published without a copyright notice, but if it was published with a copyright notice of 1959, this issue of The Owl student yearbook would have had to have been renewed in 1986. Online searches, regardless of year, of Copyright Office's Copyright Records web site for The Owl itself, editor Chris Gillotti, business manager Willard Hoel, or the University of Pittsburgh revealed no renewal entries.
This yearbook was never copyrighted or the copyright was not renewed and therefore it is in the public domain according to either criteria.
Note that it may still be copyrighted in jurisdictions that do not apply the rule of the shorter term for US works (depending on the date of the author's death), such as Canada (70 years p.m.a.), Mainland China (50 years p.m.a., not Hong Kong or Macao), Germany (70 years p.m.a.), Mexico (100 years p.m.a.), Switzerland (70 years p.m.a.), and other countries with individual treaties.
Note that it may still be copyrighted in jurisdictions that do not apply the rule of the shorter term for US works (depending on the date of the author's death), such as Canada (50 p.m.a.), Mainland China (50 p.m.a., not Hong Kong or Macao), Germany (70 p.m.a.), Mexico (100 p.m.a.), Switzerland (70 p.m.a.), and other countries with individual treaties.