By bus
By plane
Lehigh Valley International Airport IATA: ABE (http://www.lvia.org) serves the greater Lehigh Valley metropolitan area and is located about 10 to 15 minutes north of downtown Bethlehem by car. It is served by several legacy carriers, including Delta Connection, (http://www.delta.com/), Continental Express (http://www.continental.com/), United Express (http://www.united.com/), and US Airways (http://www.usairways.com/). Each offers several daily flights to their Eastern U.S. hubs. Air Canada Jazz (http://www.aircanada.ca) offers flights to Toronto, and the airport usually has at least one low-cost airline with service to Orlando-Sanford. At present, there are two; Allegiant Air (http://www.allegiantair.com) and Direct Air (http://www.visitdirectair.com). The airlines flying this route tends to change fairly often; when one budget startup goes out of business, the airport tends to replace it with another one within a few months.
The airport is on the outskirts north of the town. Take Airport Road south and get on Route 22 east; get off at the next exit for Schoenersville Road. Make a left at the end of the ramp, and follow the road until it becomes Elizabeth Avenue, at which point you are now in Bethlehem. To get to the south side, take the Route 378 exit instead of Schoenersville. When the expressway ends, make a left at the light onto S. 4th St; you are now in the south side neighborhood.
Other airports in the general vicinity are Philadelphia International Airport IATA: PHL and Newark International Airport IATA: EWR. As these are hubs for major airlines, and generally speaking much larger airports, flying into Philly or New York can save you a bundle. Expect a 90-minute drive from Philadelphia and about 2 hours from Newark, depending on traffic.
By car
Bethlehem is easily accessible by car from virtually any direction.