-Philadelphia (I don't think there was ever a Philly meet, unless it was before I was born/I've never heard about it - some were interested, so it might have merit)
The most recent AARoads-sponsored/sanctioned meet in the SEPA area was last year's (September) Golden Spike Meet covering the not-yet-opened I-95/PA Turnpike connection in Bristol, Bucks County... just northeast of Philadelphia. Despite such taking place on a weekday afternoon; there was a fairly decent turnout. Given the nature & milestone of the meet; many, no doubt, took time off from their jobs to attend.
The reasoning for the oddball date scheduling was due the meet host, briantroutman, having arranged to have some of the on-site field personnel (PennDOT/PTC/Jacobs) available to discuss the project highlights & history beforehand (I missed that part due to arriving late, I couldn't get the time off from work) prior to venturing onto the unopened ramps.
The original logistics plan for the meet was to gather at one of the construction trailers and ride to the site in one or two vans (provided by the agencies/consultants). It turned out the vans weren't available and everybody ventured out in their own vehicles (some combined/carpooled). I'm sure some passer-bys along I-95 wondered why a stream of passenger vehicles were entering a closed road/ramp between the barricades.
This past weekend (Aug. 24), Roadwaywiz95 had an impromptu video/on-line meet in Delaware County & Chester. The focus was the Commodore Barry Bridge.
Prior to 2018, the last SEPA meet I'm aware of was the Doylestown Meet that took place circa Nov. 2012 & was the first one I attended. The primary focus for that meet was the then-just-opened US 202 Parkway.