[squirrel]

Yep, sure is.
Heres something from Search and Seizure by John Wesley Hall.

1:12. -Police stops of automobiles.
Stopping an automobile and detaining its occupants is a "seizure" under the Fourth Amendment. Thus, the following stops of vehicles have been found to be "seizures" of the occupants of the vehicles: a stop to check the driver's license, a traffic stop, an investigative stop, an immigration stop either at a checkpoint or on the highway near the border, and sobriety checkpoints and other such roadblocks. Th brevity of the stop does not prevent it from being a "seizure" under the Fourth Amendment.

Traffic stop = Terry stop.
Terry v Ohio (1968) 392 US 1, 20 L Ed 2d 889, 88 S Ct 1868, 44 Ohio Ops 2d 383.