The first piano keyboard to be placed on an accordion in the U.S. emerged in the early 1900's in San Francisco by Pietro Deiro with the assistance of the Guerrini Company. After that, the piano accordion came into prominence almost worldwide and remains the most popular type of accordion used.
With the development of the Stradella bass system (a standardization of the bass button layout) the piano accordion became the first truly standardized universal accordion. This means that a piano accordionist can play any type or make of piano accordion without a change in system. This had not been possible before as there were so many different button accordions with different systems.
Multiple reed banks combined with switches give the piano accordion a huge range of notes and sounds.
Piano accordions are essentially the same as a chromatic accordion, except for a different shape to the keyboard notes and piano keyboard layout. Because of its universal note system the production of piano accordions has far exceeded that of any kind of button accordion from the 1920's until today.
