New York City

There are two international airports within the city limits: JFK and LaGuardia. Newark Liberty International Airport, just across the Hudson River in New Jersey, is a convenient cab ride from Manhattan. Major highways connect the city to the rest of the continental United States, and trains—commuter lines and Amtrak—make it easy to access New York from neighboring cities like Boston, Philadelphia, and Washington, D.C.

The New York subway is the most convenient mode of transportation within the city, with 468 stations and more than 800 miles of track. Companies like Uber are revolutionizing the way that visitors and locals catch cabs and hire car service. When in New York, however, it's always worthwhile to do as the locals do: walk. In Manhattan, city streets are largely organized in a simple grid. Don’t be afraid of a lack of options in the outer boroughs; new “Green Cabs” or “Boro Cabs” will do street pickups without complaint. The city’s fairly new bike-share program, managed by Citibike, is the most environmentally friendly option aside from walking.