Aggregate Number of Vehicles (Car, Truck, or Van) Used in Commuting
The aggregate number of vehicles used in commuting is derived by counting each person who drove alone as occupying one vehicle, each person who reported being in a two-person carpool as occupying one-half of a vehicle, each person who reported being in a three-person carpool as occupying one-third of a vehicle, and so on, then summing all the vehicles. This aggregate is used in the calculation for "workers per car, truck, or van."
Beginning in 1999, the American Community Survey questions differ from the 1996-1998 questions only in the format of the skip instructions.