The now common concert pitch of A=440 was first agreed upon in the mid 1900s in Europe. Earlier pitches were lower. France set the standard pitch to A=435 in 1859.
A concert pitch was also known for the action for tuning a piano which needed to be done for a concert. During concerts in the 19o0's they often need to tune the piano frequently as it was used for every show and often had a lot of wear and tear.
