Postmarked July 1963.
This was printed on fast paper using an enlarger. Prior to 1926 there were no photo papers available with a stable emulsion, and so most photos taken before them have yellowed to some degree. The sulfur Hypo solutions used to wash out excess silver and fix the print cannot be entirely washed off and they tend to yellow in time. Older papers also often had unappealing coloration so they were toned or printed on dyed paper to compensate. Because of this it is rare to see a black & white photograph that is truly a neutral black & white before the 1930’s. The new faster papers that were made specifically for the enlarging process that became popular in the 1930’s are generally brighter and glossier but do not hold as much detail.