I've had three departures out of DCA over the past month, and each time the dedicated SkyPriority lane was policed by an employee of DL's contract assistance company, and the wait was considerably shorter than in the regular line. As you approach security from the direction of the Metro Station and the bottom of the escalator from the ticket counters, stay to the left.

I can confirm that SkyPriority was working very well at MCI on Saturday; I bypassed about 100 pax waiting to clear security at the DL gates.

I can also confirm that there is no SkyPriority at SMF and at BHM. Since Southwest has departed Terminal A at SMF and has been replaced by United, there seems to be no reason why UA/CO, US and DL can't collaborate on an elite lite. All of BHM's operations are out of one concourse these days as there is only a steel skeleton where the AA/US concourse once was, and there is no elite line there.