Terminology

For the purposes of this blog I've chosen a set of popular definitions for terms that are likely to appear frequently. Of course many of these definitions vary, but these are the most common and straightforward.

Regional Terms

Metro Area: Area consisting of a highly populated city core and its surrounding suburban (and exurban) counties. Included counties must be at most two counties removed from the principal city or have at least 100,000 residents.

Baltimore Metropolitan Area: Baltimore City (MD), Anne Arundel County (MD), Baltimore County (MD), Carroll County (MD), Harford County (MD), Howard County (MD), Queen Anne's County (MD)

Washington Metropolitan Area: Washington, D.C., Calvert County (MD), Charles County (MD), Frederick County (MD), Montgomery County (MD), Prince George's County (MD), Howard County (MD), Arlington County (VA), Fairfax County (VA), Loudoun County (VA), Prince William County (VA), Stafford County (VA), Alexandria and other independent cities in Northern Virginia

Baltimore-Washington Metropolitan Area: Baltimore Metro Area + Washington Metro Area

Mid-Atlantic: New York, New Jersey, Pennsylvania, Delaware, Maryland, Washington D.C., [Northern Virginia]*, [West Virginia]*

New England: Maine, New Hampshire, Vermont, Massachusetts, Rhode Island, Connecticut

Northeast: New England + Mid-Atlantic

*The state of Virginia is commonly defined as Southern, but for the purposes of this blog Northern Virginia will counted as part of the Mid-Atlantic, due to its economic and cultural ties to the Washington Metro Area. West Virginia is a very unique state located almost entirely in the rural geographic Appalachian region, but it shares many cultural traits with it's immediate Southern, Midwestern, and Northeastern neighbors. For the purposes of this blog it will be defined as Mid-Atlantic.

Locality Definitions

Major Town: 25,000-50,000 residents

Small City: 50,000-100,000

Mid-Sized City: 100,000-500,000 residents

Large City: 500,000+ residents

Low Density: <5,000 residents/sq. mi.

High Density: >5,000 residents/sq. mi.

Transportation Terms
Highway: Major vehicular roadway (usually designated as a State/US Route).

e.g. Midcounty Highway/MD Route 124

Freeway/Expressway: Controlled access highway

e.g. I-270 (Maryland)

Local Bus: Conventional city bus service making short-distance trips with frequent stops (except for select express services) on multiple routes each serving  a small geographic area within a city or suburb.

e.g. WMATA Metrobus, RideOn

Bus Rapid Transit: High frequency bus service using dedicated right-of-way for at least part of the its route.

No true BRT routes currently exist in the Baltimore-Washington Metro Area, but WMATA's Metrobus uses BRT buses for many of it's routes:

Commuter Bus: Express coach service with routes from urban cores to suburbs and exurbs. 

e.g. MTA Commuter Bus

Intercity Bus: Long distance coach bus that carries passengers significant distances between different cities or towns, usually with a single, centralized stop in each town/city.

e.g. Greyhound, Bolt Bus

Light Rail (including streetcars, trams, and trolleys which have lower capacities but otherwise very similar):  Mode of rail transit service  usually operating trains consisting of 1-3 rail cars on rail right-of-way that is often shared with automobile traffic for part or much of the way. Light rail vehicles are typically driven electrically with power being drawn from an overhead electric line, but can also be diesel powered. Light rail systems usually have more frequent stops, slower speeds, and lower capacities than heavy rail systems.

e.g. MTA Light Rail (Baltimore)

Heavy Rail/Rapid Transit (also called subway, metro): Rail transit mode usually electrically powered with the capacity to handle a heavy volume of traffic (more than light rail). It is characterized by (relatively) high-speed trains 2-10 rail cars long running in its own dedicated right-of-way often above or underground, rapid acceleration passenger rail cars (EMU's), and high platform boarding.

e.g. WMATA Metrorail

Commuter Rail (also called regional rail): Rail service that primarily operates between a city center and suburbs and exurbs. Trains operate following a schedule, at speeds varying from 30 to 125 mph. Trains are usually powered electric or diesel locomotives, but some systems use self-propelled rail cars called Multiple Units (MU's). Commuter rail is generally characterized by the availability of multi-trip tickets, specific station to station fares, conductors on-board, railroad employment practices, and usually only one or two stations in a central business district with the rest being suburban/exurban.

e.g. MARC Train

Inter-city Rail: Rail services with stops in multiple major cities serving a number of states. In the United States Amtrak is the only operator of inter-city rail services and the vast majority of routes utilize trains powered by diesel locomotives and run on relatively low frequencies (3 times daily or less). The Amtrak routes serving most of the country are long distance routes of 500 miles or longer. In the Northeast and California there are a number of high frequency, heavily traveled intermediate length routes.

e.g. Amtrak Coast Starlight

High-Speed Rail: For the purposes of this blog high-speed rail is defined as inter-city rail services with top speeds of 125mph or greater. Currently the only such services are Amtrak's Acela Express (top speed of 150mph) and Northeast Regional (top speed of 125mph) services which operate along the Northeast Corridor.

e.g. Amtrak Acela Express