The Mid-Atlantic region of the United States of America comprises five states and a federal district along the eastern seaboard. While the region is dominated by the enormous megalopolis running from Washington, D.C. to New York City, it is balanced by large areas of more rural character to the north and west. It borders New England to the northeast, the Midwest to the west, and the South, naturally, to the south. The Canadaian province of Ontario is to the north.
The Mid-Atlantic is a bit of an odd cultural region, in that its most prominent shared characteristics are that of a region between more culturally coherent regions. It is at times a bit southern, at other times northern, or even a bit midwestern in Western New York. Accordingly, individual states and cities (even more so) tend to have strong individual identities and locals are more likely to identify with a strong subregion like the New York City tri-state area, the D.C. metropolitan area, rural Pennsylvania, "New Joisey," etc., than to identify with the Mid-Atlantic as a whole.
The other defining aspect of the Mid-Atlantic culture is an interrelated combination of high population density and rude driving (see the Get around section). Three of the USA's top ten metropolitan areas are located here: New York, Philadelphia, and Washington, D.C., spaced apart from each other by only about 1.5-hour's-drives. These metro areas consist of immense urban sprawl radiating out from the city centers, covering nearly the entire region (save much of Pennsylvania and upstate New York). Their huge populations ensure that the roads remain congested, beaches well attended, and paths well-beaten.
The areas outside these mega cities are much less frequently visited by international tourists, but there is nonetheless much more to be seen. The Chesapeake Bay is a true world treasure and should not be missed by anyone interested in ecology, sailing, or seafood.
This is a real East Coast region, with all the associated stereotypes of huge immigrant communities from all over the world, leftist politics aplenty, parents pushing their children to become overachievers, good food, and a vaguely arrogant (and ignorant) attitude towards the rest of the country. The long Atlantic Coast also means that the region has stronger ties, in terms of travel, culture, and commerce, with Europe.
As with the majority of the United States, all official signs in the Mid-Atlantic are in English and travelers speaking English should have little difficulty communicating there needs wherever they go. Spanish is widely spoken, mostly by immigrants from Latin America and their families, although the language is also taught poorly to the majority of the native-born population.
Because these five states lie on the East Coast, they were the initial point of entry for most English-speaking immigrants and as such, have retained a much greater degree of diversity in terms of regional accents than the rest of the country (accents tended to converge as settlers went west). While you are likely to just encounter General American Pronunciation pretty much wherever you go, you may be treated to a New Yorker accent in Brooklyn, Long Island, or northern New Jersey; Bawlmorese in Baltimore, the baffling -to-linguists Picksburg accent that just keeps diverging ever farther from surrounding accents, a South Philly accent, or southern accents on Maryland's Eastern Shore. You can even find 17th century English accents if you look for them among the isolated island communities of the Chesapeake Bay!
The principal points of entry are the regions airports and the super hubs are in the New York and Baltimore-Washington metro areas. The former is served primarily by John F Kennedy International airport (IATA: JFK), Newark Liberty Airport (IATA: EWR), and LaGuardia Airport (IATA: LGA), while the latter is served by Washington Dulles International Airport (IATA: IAD), Reagan Washington National Airport (IATA: DCA), and Baltimore Washington International Airport (IATA: BWI). Philadelphia is served mainly by just one airport, Philadelphia International Airport (IATA: PHL), which is accordingly the largest in the area. Other cities in the area will often have their own airports, but direct flights may be harder to come by.
Greyhound is unfortunately the main intercity bus operator, unfortunately because it is an inefficient and expensive way of getting around. Fortunately it is seeing low-cost competition from a peculiar set of Chinatown bus routes. These no frills point A to point B services arose organically from the needs of Chinese-Americans to visit their relatives in the various Chinatowns across the region. The service caught on when the general public realized they could travel round trip from D.C. to New York for $30. There is no central internet site for these services, so you are best off doing a general internet search. Be aware that the Chinatown buses do occasionally terminate and originate in unsavory urban neighborhoods.
A new wave in intercity coach transportation is large corporations trying to emulate Chinatown buses but with better services. Megabus  was the first to embrace the new business model, offering heavily discounted fares from its New York hub to Boston, Toronto, Buffalo, Philadelphia, Baltimore, Atlantic City and Washington. Bolt Bus  is a division of Greyhound but is significantly cheaper and more comfortable than their regular services, they provide newer coaches wit more legroom, electric sockets at every seat and free wireless internet. Bolt Bus provides journeys within the northeast corridor, almost identical to Megabus. Ne-On  is also a division of Greyhound and operates between New York City and Toronto, via Buffalo, their on-board services match those of Bolt Bus.
While train service is very limited in the rest of the United States, the Northeast has by far the best rail service in the country. The high-speed Acela express runs frequently along the Washington-Philadelphia-New York-Boston corridor. Amtrak also serves upstate NY, and western PA.
In addition to frequent Amtrak service, there are a number of regional (commuter) rail lines including: MTA Metro North and Long Island Railroad, NJ Transit, Shore Line, SEPTA, and MARC. It is possible to travel much of the coast using only regional rail, and although it will probably be slower than the Amtrak or Acela Express, it will also cost a fraction of the price, and may just take you through towns you might not otherwise see. If you intend to visit cities, rail travel may be your best option.
All states in this region maintain convenient service plazas along the major highways, which are probably your best bet for hitchhiking as the freeway itself is closed to pedestrians.
I-95 is the coastal super highway, at times encompassing a whopping eighteen lanes, and connects D.C. to New York through Baltimore, Philadelphia (optional), and pretty much everything in between in New Jersey and Delaware. It is the fastest way to drive between these cities, but it is unpleasant and ridden with expensive tolls (especially in Delaware!) and very bad traffic on weekends and around local rush hours. Avoiding I-95 requires a bit of creativity and slightly longer trips through Pennsylvania west of Philadelphia, but such trips can be rewarding in terms of scenery, no tolls, little traffic, and just easier traveling generally.
Finally, a direct warning is in order: Driving into D.C. and New York is really not advisable. Doable, certainly; fun, not likely. Washington D.C.'s street layout was designed to confuse invading armies. New York is extremely congested, and its drivers are the most aggressive in all of North America (although those driving in Boston can dispute that claim.) If you are driving into D.C., get good directions and don't do it anywhere around rush hour. If driving into New York, save yourself by parking in a less congested borough (like Queens or Brooklyn), where you might actually find free on-street parking, and take a subway line from there into Manhattan. Driving in Mid-Atlantic cities is really not recommended however because it is not necessary; Mid-Atlantic cities have the best mass transit systems in North America. It is almost always better to take a train in and use mass transit than to drive in and pay astronomical parking expenses.
Although there are lots of budget flight options between cities on the Mid-Atlantic, due to the hassles and delays associated with increased security precautions, especially in the New York City area, short flights are usually best avoided. All major cities are connected by regional and commuter rail options with stations in the central business districts of these destinations. Moreover, most inter-city planes travel between suburban airports fairly far out from the city center. When the distances are long enough, though, flights can indeed be cheap and convenient, from, say, Washington, D.C. to Albany, or New York to rather far-flung Pittsburgh.
If visiting the Mid-Atlantic, you may want to take a look at the following itineraries:
Much of the Mid-Atlantic is afflicted by so much suburban sprawl that there isn't much to do other than go to the movies. But peer a bit further into the region, and there are magnificent outdoor opportunities in the west and north. For hikers, the longest trail in the world runs from Georgia to Maine, passing through Maryland, Pennsylvania, and New York. Pennsylvania between Pittsburgh and Philadelphia, is beautiful and largely wild. Drives through pastoral Amish country or hikes through thickly forested hills are a great way to get away from the huge urban centers of the region. Way up in the northern section of New York is the enormous Adirondack State Park—the largest state park in the country, spanning an area larger than next door Vermont. Possibilities there for kayaking, boating, hiking, camping, hunting, and fishing are pretty much endless. The most popular escapes, however, are to the region's beaches in the summer, in the Jersey Shore and in Delaware and Ocean City, where you can get a good tan, go swimming, gamble in some places, and eat boardwalk fries to your heart's content.
Sporting events are another huge draw to the region, with at least one major national team in each major city for each major league. The region also hosts minor league teams, such as the Lehigh Valley IronPigs, the AAA-level Philadelphia Phillies team, based in Allentown.
If you know where to go, the Mid-Atlantic is a food-lovers paradise. New York City has the world's best upmarket dining scene hands down. The D.C. area has an unlimited supply of cheap, delicious, immigrant-run restaurants featuring cuisines from every corner of the world. Philadelphia takes its fast food seriously and is an excellent place to try American street food including, of course, the Philly Cheeseteak. New Jersey's diners are iconic, Baltimore's are funky as they come. And the coastal areas of Delaware and Maryland are rightly famous for their magnificent crab feasts.
Few parts of the world can boast the nightlife to be found in the urban areas of the Mid-Atlantic. New York City's nightlife probably needs no introduction. From the diviest dives to the swankiest wine bars, as well as the best jazz in the world, New York's really got it all in this category. Philadelphia, Allentown, and Baltimore offer quirky, rougher-edged, and less accessible, but very lively bar and clubbing scenes. Pittsburgh defies post-industrial-city expectations with a lively and surprisingly classy nightlife scene. Washington, D.C. would at first glance seem the exception, with its reputation for bland, poorly dressed staidness and early closing times. The early closing times are a bummer on weekdays, but weekends have become hot for clubbers in the last 5–10 years.
Local drinks are many, mostly in the beer category.
As is true for much of the United States, crime is a problem in the inner cities, while city outskirts, suburbs, and the countryside are almost always quite safe. Washington, D.C., Philadelphia, and Baltimore are particularly risky for travelers--they all are worth visiting, but have rough neighborhoods near many popular tourist sites—best to do your research ahead of time and avoid straying off the beaten path. New York, despite what you may have seen in the movies, is actually one of the safest big cities in the country, and, you may rest easy knowing that violent crime has become rare in areas frequented by tourists. The main cities of New Jersey are less of a concern, as they are not at all major travel destinations. Bear in mind, however, that Newark, Camden and Trenton are all non-destinations because of their high levels of violent crime.
The upside to staying safe in the Mid-Atlantic is that there is no better place on Earth to develop a brain tumor, get knived, or crash your car—it is home to the best hospitals in the world in Baltimore (Johns Hopkins), and the New York City, Philadelphia and Washington, D.C. metro areas. Indeed, the hospitals get visits from the elite of the world, ranging from third world dictators to jet-setting millionaires. If they can't repair you, nobody can.