ADULT - A person 16 years and older.

HOUSEHOLD - a group of persons whose usual place of residence is a specific housing unit. These persons may or may not be related to each other. The total of all U.S. households represents the total civilian, non-institutionalized population. This category does not include group quarters (i.e., 10 or more persons living together, none of whom are related).

HOUSEHOLD VEHICLE- a motorized vehicle that is owned, leased, rented, company-owned, or available under some other arrangement, such as borrowed. The vehicle must be available to be used regularly by household members during the travel period. Also included are vehicles used solely for business purposes or business-owned vehicles if kept at home and used for the home to work trip, (e.g., taxicabs, police cars, etc.) which may be owned by, or assigned to, household members for their regular use. Vehicles that were owned or available for use by members of the household during the travel period even though a vehicle may have been sold before the interview are also included. Excluded from this category are vehicles that were not working and not expected to be working within 60 days, and vehicles that were purchased or received after the designated travel day.

JOURNEY-TO-WORK - Includes travel to or from a place where one reports for work. Does not include any other work-related travel.

MEANS OF TRANSPORTATION - A mode used for going from one place (origin) to another (destination). Included are private and public modes, as well as walking. For all travel day trips, each change of mode constitutes a separate trip. The following transportation modes, grouped by major mode, are included:

Private Vehicle

• Automobile: A licensed motorized vehicle, including cars, jeeps, and station wagons.
• Van: Vans and minivans designed to carry passengers or to haul cargo.
• Pickup: A motorized vehicle with an enclosed cab that usually accommodates two to three passengers and an open cargo area in the rear. Pickup trucks usually have about the same wheelbase as a full-size station wagon.
• Other Truck: All trucks other than pickups (such as dump trucks and trailer trucks)
• RV or Motor Home: Includes self-powered recreational vehicles that are operated as a unit without being towed by another vehicle.
• Motorcycle: Includes large, medium, and small motorcycles. Does not include minibikes, which cannot be licensed for highway use.

Public Transportation

• Bus: Includes intercity buses, mass transit systems, buses, and shuttle buses that are available to the general public. Also included are Dial-A-Bus and Senior Citizen buses that are available to the public. Excluded from this category are (1) shuttle buses operated by a government agency or private industry for the convenience of employees, or (2) contracted or chartered buses or school buses.
• Commuter Train: Includes local and commuter train service other than elevated rail and subway. Intercity service by Amtrak is excluded.
• Streetcar/Trolley: Includes trolleys, streetcars, and cable cars.
• Elevated Rail/Subway: Includes elevated rail and subway trains.

Other Modes

• Airplane: Includes commercial airplanes and small planes that are available for use by the general public in exchange for a fare. Private planes and helicopters are included under "other".
• Taxi: The use of a taxicab by a passenger for a fare. Also included are airport limousines.
• Bicycle: Includes bicycles of all speeds and sizes that do not have a motor.
• Amtrak: The U.S. national passenger railroad service providing intercity train service.
• Walk: Includes walking to a destination. Excluded is walking for exercise where the trip origin and destination are the same.
• School Bus: Includes county school buses, private school buses, and buses chartered from private companies for the express purposes of carrying students to or from school and/or school-related activities.
• Moped (motor bicycle): Includes motorized bicycles equipped with a small engine, typically 2 horsepower or less. Also included are minibikes such as dirt bikes and trail bikes. Note that a motorized bicycle may or may not be licensed for highway use.
• Other: Includes any type of transportation not listed above.

OCCUPANCY (Vehicle) - The number of persons, including driver and passenger(s) in a vehicle. NPTS occupancy rates are generally calculated as person miles divided by vehicle miles.

PERSON MILES OF TRAVEL (PMT) - A measure of person travel. When one person travels one mile, one person mile of travel results. When one person travels five miles, five person miles of travel results. When four persons travel five miles in the same vehicle, 20 miles of travel result.

PERSON TRIP - A person trip is a trip by one person in any mode of transportation. If more than one person is on the trip, each person is considered as making one person trip. For example, four persons traveling together in one auto account for four person trips.

TRAVEL DAY - A 24-hour period from 4:00 am to 3:59 am of the following day designated as the reference period for studying trips and travel of a particular household.

TRAVEL DAY TRIP - A travel day trip is defined as any one-way travel from one place (address) to another by any means of transportation (e.g., private vehicle, public transportation, bicycle, walking). When travel is to more than one destination, a separate trip exists each time the following criteria are satisfied: the travel time between two destinations exceeds 5 minutes, and/or the purpose for travel to one destination is different from the purpose for travel to another.

The one exception is travel within a shopping center or mall. It is to be considered travel to one destination regardless of the number of stores visited.

TRIP PURPOSE - The main reason that motivates that trip. For purposes of this survey, there are 11 reasons for trips. For travel day trips, if there is more than one reason for the trip, and the reasons do no involve different destinations, then only the main reason is chosen. If there are two or more reasons, and they each involved different destinations, then each reason is classified as a separate trip. For travel period trips, if there was more than one reason, the primary reason was collected. The 11 trip reasons (grouped into the four major purposes) are defined as follows:

Earning a Living

• To or From Work: Includes travel to a place where one reports for work. Does not include any other work-related travel.
• Work-Related Business: Trips related to business activities except travel to the place to work, e.g., a plumber drives to a wholesale dealer to purchase supplies for his business.

Family and Personal Business

• Shopping: Includes purchases of commodities such as groceries, furniture, clothing, etc., for use or consumption elsewhere.
• Doctor or Dentist: Trips made for medical, dental, or psychiatric treatment or other related professional services.
• Other Family or Personal Business: Includes purchase of services such as cleaning garments, haircuts, and car repair and maintenance. Also includes trips to take someone else somewhere, i.e. "serve passenger" trips.

School or Church

• School/Church: Trips to school, college, or university for classes, PTA meetings, seminars, etc., to church services or to participate in other religious activities. Social activities that take place at a church or school are classified as social and recreational.

Social and Recreational

• Vacation: Trips reported by the respondent as "vacation".
• Visit Friends or Relatives: Trips made to visit friends or relatives.
• Pleasure Driving: Includes trips made with no other purpose listed but to "go for a drive" with no destination in mind, but strictly for pleasure.
• Other Social and Recreational: Any purpose for a trip that does not fit into one of the above categories. For example, going to dinner with friends, attending movies/theater, etc.

VEHICLE - All motorized vehicles including autos, passenger vans, pickup trucks, and other light trucks, RV's, motorcycles and mopeds owned or available to the household. NOTE: The 1969 NPTS did not include pickups and other light trucks, RV's, motorcycles and mopeds.

VEHICLE MILES OF TRAVEL (VMT) - A unit to measure vehicle travel made by a private vehicle, such as an automobile, van, pickup truck, or motorcycle. Each mile traveled is counted as one vehicle mile regardless of the number of persons in the vehicle.

VEHICLE TRIP - A trips by a single vehicle regardless of the number of persons in the vehicle.