Since Porgy and Bess was based in the South, Gershwin stayed in Folly Beach, South Carolina and wrote it there. Of course, he needed a piano, so he visited the local music store, Siegling's Music House, and chose a Matchless Cunningham Piano. That piano is now on public display at The Charleston Museum.
"Cunningham Piano Company, coincidentally also from Philadelphia, has been building pianos for symphonies, academies, and concert pianists since the 1890's and they were treasured by those who played them. Considering my rudimentary skill level, I was humbled to own one."