Quoting from the DC Circuit opinion in "EPIC v. Department of Homeland Security":
"""As other circuits have held, and as the Supreme Court has strongly suggested, screening passengers at an airport is an "administrative search" because the primary goal is not to determine whether any passenger has committed a crime but rather to protect the public from a terrorist attack. See United States v. Aukai, 497 F.3d 955, 958–63 (9th Cir. 2007) (en banc) (passenger search at airport checkpoint); United States v. Hartwell, 436 F.3d 174, 178–81 (3d Cir. 2006) (Alito, J.) (same); United States v. Edwards, 498 F.2d 496, 499–501 (2d Cir. 1974) (Friendly, J.) (carry-on baggage search at airport); see also Illinois v. Lidster, 540 U.S. 419 (2004) (police set up checkpoint to obtain information about earlier crash); Mich. Dep’t of State Police v. Sitz, 496 U.S. 444 (1990) (sobriety checkpoint). An administrative search does not require individualized suspicion. City of Indianapolis v. Edmond, 531 U.S. 32, 41, 47–48 (2000) (individualized suspicion required when police checkpoint is “primarily [for] general crime control,” that is, “to detect evidence of ordinary criminal wrongdoing” unlike “searches at places like airports ... where the need for such measures to ensure public safety can be particularly acute”). Instead, whether an administrative search is “unreasonable” within the condemnation of the Fourth Amendment “is determined by assessing, on the one hand, the degree to which it intrudes upon an individual’s privacy and, on the other, the degree to which it is needed for the promotion of legitimate governmental interests.” United States v. Knights, 534 U.S. 112, 118-19 (2001) (internal quotation marks omitted)."""
The Edwards reference you mentioned is in there, but so are others. In "United States v. Aukai" (2007) the 9th Circuit said "We have held that airport screening searches, like the one at issue here, are constitutionally reasonable administrative searches because they are "conducted as part of a general regulatory scheme in furtherance of an administrative purpose, namely, to prevent the carrying of weapons or explosives aboard aircraft, and thereby to prevent hijackings."
In United States v. Hartwell (3d Cir. 2006), para. 8 "We hold that the search was permissible under the administrative search doctrine. Cf. United States v. Marquez, 410 F.3d 612, 616 (9th Cir.2005) ("Airport screenings of passengers and their baggage constitute administrative searches and are subject to the limitations of the Fourth Amendment.").
These were all easy to find.