Green’s Dictionary of Slang

(US) Philadelphia, PA.

1813		Vermont Republican (St Albans, VT) 20 Nov. 2/4: Riot in Philadelphia — The Quaker City [...] has been the scene of several disgraceful riots [etc].
1851		Sunbury Gaz. (PA) 11 Jan. 3/3: Philadelphia enterprise and capital have been too slow [...] This need be no cause of alarm to the Rip-van-Winkle unconcern of the Quaker City.
1891		Nat. Police Gaz. (NY) 24 Jan. 6/2: [A]fter he had tied the marriage knot they started at once for the Quaker City.
1921		N. Putnam West Broadway 78: We ate and beat it, and done our best getting out of the Quaker City.
1935		T. Yates ‘Harlem on My Mind’ in Afro-American (Baltimore, MD) 2 Mar. 9/4: The plump Quakertown lassie deserts that town.
1938		Pittsburgh Courier (PA) 22 Oct. 11/1: Stump and Stumpie are holding forth in the Quaker City after cancelling their European tour.
1942		Pittsburgh Courier (PA) 18 July 21/1: Sepia Quaker City dwellers are still yellin’ that Bob Montgomery was robbed.