By car
Pennsylvania is a densely populous state in a densely populous part of the country, with many roads in and out. Interstate highways lead most traffic into the state. Major national interstate highways leading to Pennsylvania include I-95 S from New England, I-95 N from the American South, and I-70 E, I-80 E & I-90 E from the American West and Midwest. Specifically, clockwise from north of Harrisburg:
from Montreal & Ottawa to Scranton & Harrisburg: I-81 S.
from Boston to Scranton: I-90 W to I-84 W.
from Boston to the Lehigh Valley & Harrisburg: I-84 W to I-91 S to I-95 S to I-287 W to I-78 W.
from Boston to Philadelphia: I-84 W to I-91 S to I-95 S.
from New York City to Scranton: I-80 W.
from New York City to the Lehigh Valley & Harrisburg: I-78 W.
from New York City to Philadelphia: I-95 S.
from Baltimore to Philadelphia: I-95 N.
from Baltimore to Harrisburg: I-83 N.
from Baltimore to Pittsburgh: I-70 W.
from Washington, DC to Philadelphia: I-95 N.
from Washington, DC to Harrisburg: I-95 N to I-83 N.
from Washington, DC to Pittsburgh: I-270 W to I-70 W.
from West Virginia to Pittsburgh: I-79 N.
from Columbus & Indianapolis to Pittsburgh & Harrisburg: I-70 E.
from Cleveland to Pittsburgh: It's close, but complicated.
from Cleveland & Chicago to Erie: I-90 E.
from Toronto & Buffalo to Erie: I- 90 W.
Also, U.S. Routes 219, 15, and 220 soon to be I-99 all enter the state at alternative points from both the north and south.
State-operated Welcome Centers and Comfort Facilities are located just inside the borders at all major crossings into Pennsylvania.
By train
Amtrak offers a total of nine different passenger train lines in or across the state of Pennsylvania. A fair amount of these run between New York and Philadelphia, continuing to points south, such as Charlotte, and New Orleans. The Pennsylvanian crosses a large swath of the state during its journey from New York to Pittsburgh, and the Keystone travels from New York to Harrisburg. Pittsburgh and Philadelphia are also each connected to Chicago and Washington D.C.
By plane
The two major airports in Pennsylvania are Philadelphia International Airport IATA: PHL, ICAO: KPHL and Pittsburgh International IATA: PIT, ICAO: KPIT. Philadelphia is a major hub for US Airways and Pittsburgh is a large focus city for the same carrier. Both are served by all major carriers and have low fare service by Southwest and AirTran Airways. Philadelphia is also one of the Northeast's major international termini, with flights to an array of European destinations.
Regional airports in Pennsylvania include Lehigh Valley, Harrisburg and Wilkes-Barre/Scranton. All of these airports are served by US Airways, US Airways Express, Delta, Northwest and Continental.