This writer is the only one in Philadelphia who claims Philadelphia in no longer a boxing capital. There are no longer any champions since Danny Garcia lost his welterweight title in 2017.
Danny Dougherty was the first Philadelphia champion being the World Bantamweight Champion from 5/26/1900 to 4/30/1901. Philadelphia has had 40 world champions but currently none.
Heavyweight champions: Sonny Liston 1962-64, Joe Frazier 1970-73, Tim Witherspoon 1/86-12/86,
Cruiserweight champions: Nate Miller 1995-97, Steve Cunningham 2007-08, Steve Cunningham 2010-2011
Light Heavyweight champions: Philadelphia Jack O’Brien 1905-12, Battling Levinsky 1916-20, Tommy Loughran 1927-29, Harold Johnson 1961-1963, Mike Rossman 1979-81, Matthew Saad Muhammad 1979-81, Bernard Hopkins 2006-08, Bernard Hopkins 2011-12, Bernard Hopkins 2014 Apr-Nov
Super Middleweight champions: Charles Brewer 1997-98
Middleweight champions: Joey Giardello 1963-65, Bernard Hopkins 1995-2005, Bernard Hopkins 2001-05
Super Welterweight champions: Buster Drayton, 1986-87, Robert Hines 1988-89, David Reid 199-2000
Welterweight champions: Harry Lewis 1908-11, Meldrick Taylor 1991-92, Danny Garcia 2016-17
Super Lightweight champions: Johnny Jadick 1932 for 8 months, Gary Hinton, 4/86-10/86, Meldrick Taylor 1988-90, Danny Garcia 2012-15
Lightweight champions: Bob Montgomery 1944-47, Charlie Brown 1984-Jan to April, Fred Pendleton 1993-94
Super Featherweight champions: Benny Bass 1929-31
Featherweight champions: Benny Bass 1927-28, interim Percy Bassett 1953-54
Bantamweight champions: Danny Dougherty 1900-01, Jeff Chandler, 1980-84
Flyweight champions: Midget Wolgast 1930-35
Per Fight News, Philadelphia has 10 Contenders:
HW: Bryant Jennings No. 13 WBA, Amir Mansour No. 13 WBO
CRUISER: Steve Cunningham No. 15 IBF
SUPER MIDDLE: Jesse Hart No. 3 WBC No. 1 WBO
SUPER WELTER: Julian Williams No. 15 WBA No. 6 WBO, Tyrone Brunson No. 15 IBF
WELTER: Danny Garcia No. 2 WBC No. 1 WBA
LIGHTWEIGHT: Hank Lundy No. 11 WBC
SUPER LIGHTWEIGHT: Tevin Farmer No. 9 WBC No. 4 IBF, Avery Sparrow No. 14 WBO
With no current champions and 10 contenders I believe its fine to say Philadelphia is no longer a fight capital in US boxing.