Newark Liberty International Airport (IATA code EWR) is the oldest commercial airport serving the New York metropolitan area, and the second-largest after NYC's own JFK Airport.
In 1927, despite some advances in Europe, air transport in America was still a collection of tiny biplane operators on short routes, and there was nothing resembling a national airline network. The man who gave the country its needed wake-up call was Charles Lindbergh, and shortly after his record flight to Paris in the Spirit of St. Louis, the United States Postal Service broke down and decided to subsidize a new network of air routes that would connect major cities across the country, supplementing the existing railway networks. After looking around the New York area, the Department of Commerce decided that the best spot to build an airport would be atop a garbage dump in Newark, New Jersey, across the Hudson River from Manhattan. Newark's city government gave its blessing to the project, and began building the airport in January of 1928. The airport opened on October 1st, costing $1.75 million to construct: among its ultra-modern features, it had the first paved runway in America.
In its early years, the airport grew quickly. By 1930, it was already the busiest commercial airport in the world. In 1935, Amelia Earhart participated in the opening of the airport's first passenger terminal, which some believe to be the first commercial airline terminal in the world. (This building was physically moved over one mile away in 2000, and is now a museum and administration building for the airport.) Being built on a dump, the airport was plagued early on by giant rats, some large enough to eat through the plumbing in the terminal and hangars.
However, Newark's primacy was short-lived. Fiorello LaGuardia was adamant about developing a new airport in New York, and after a brief attempt to bring commercial service to Brooklyn's Floyd Bennett Field, he ordered a new airport built in northern Queens, which we now know as LaGuardia Airport. LaGuardia opened in 1939 and stole a great deal of Newark's air traffic overnight. Not long afterward, Newark Airport was closed for commercial use, and through the end of World War II it was solely used by military aircraft.
In 1948, the airport was handed over to the Port Authority of New York and New Jersey (which also took over LaGuardia and the then-new Idlewild Airport, now known as JFK). The Port Authority opened the airport to commercial flights again, and constructed a new passenger terminal in 1953 to handle the increased demand. Although passenger traffic was fairly low during the 50s and 60s, Newark became a fairly large air cargo hub. In 1973, the Port Authority opened two new terminals, now known as "A" and "B."
Then came airline deregulation, in 1978. New carriers began popping up across America. One new airline, People Express, began operating from Newark in 1981, and within a few years, it had become one of the largest airlines in the United States, and had effectively brought Newark Airport back from the dead. In the meantime, Virgin Atlantic Airways began its first London-New York flights through Newark in 1984, competing with British Airways' hefty operations at JFK (as well as JFK-based Pan Am and TWA).
In 1987, People Express was bought out by Houston-based Continental Airlines. Continental moved into the new Terminal C in 1989 and has continued to expand its operations at Newark up through the present day, with nonstop flights to cities throughout Europe, South America, and Asia.
During the patriotic upsurge in the wake of September 11, 2001, Newark International Airport was officially renamed "Newark Liberty International Airport," although its common name is still "Newark Airport."
Newark Airport today
Newark Airport is no longer the busiest airport in the world, nor is it the busiest airport in New York. However, it is the 12th-busiest airport in the United States, ranked 18th worldwide, and is also the third-largest transatlantic gateway in America after Chicago and JFK. It is one terminus of the longest scheduled nonstop flight in the world, Singapore Airlines' 18-hour run between Newark and Singapore.
Continental is Newark's dominant operator by a long shot, accounting for about half of the airport's passenger traffic (65% if you include Continental Express flights). The airport handles 550 scheduled flights a day (on average) to 80 U.S. airports and 63 destinations overseas, and ushers on 33 million passengers and 1 million tons of cargo a year.
EWR was the first multimodal airport in the New York area, and remains the easiest to access by public transportation (although this is only relative, because JFK is only accessible by a long subway ride, and LaGuardia only by bus). The airport is connected by monorail (the "AirTrain") to a dedicated train station on Amtrak and NJ Transit's Northeast Corridor Line, allowing direct rail connections throughout New Jersey and even as far as Boston and Washington, DC. (Woe betide you if the monorail isn't working, though: this happened to me at Newark a couple of weeks ago, and I ended up carrying my bags from the parking garage to Terminal A, a hike no noder should have to undergo on a summer morning).
Many airlines from around the world fly to Newark today: you can see aircraft in the liveries of Air India, Alitalia, CSA, El Al, EVA Air, LOT Polish Airlines, Malaysia Airlines, and TAP Air Portugal, to name a few. Newark is also one of the few airports served by Hooters Air, whose stewardesses offer coffee, tea, and boobies on flights to Myrtle Beach, South Carolina.
All in all, Newark is a decent airport, corrupted by its bizarre New Jersey surroundings and the accompanying roadway disorganization and random wacko visitors/employees/administrators. But it's no worse than other airport choices around NYC, with the possible exception of the Downtown Manhattan Heliport.