In July of 1986, the Phoenix City Council approved one of the most ambitious building projects in Sky Harbor's history — the design and construction of a giant new terminal building. Terminal 4 broke ground in October, 1989 and opened in November, 1990. At $248 million, Terminal 4 was the largest structural capital improvement project in Phoenix. Construction began on the terminal core and three concourses — two for use by what was then America West Airlines and one for international arrivals — but prior to completion, a route expansion by Southwest Airlines required that it too be located in Terminal 4. Two more concourses were added and the building opened in November, 1990 with five concourses and 44 gates.
Terminal 4, with 44 gates and 3.9 million square-feet of space, handled 15.4 million passengers or 70 percent of Sky Harbor's total traffic in 1991. In 1998, a sixth concourse was added and the international concourse was expanded to include more gates.
In March 2005, a new concourse opened in Terminal 4, providing gates D1 to D8 and a new checkpoint. The concourse, the seventh in this terminal, comprises an area of 180,000 square feet and is 140 feet wideó50 feet wider than the other concourses. Designed with a more modern look in mind, the new concourse includes a high roof, beams, clerestory windows and a Terrazzo floor. Terminal 4 was designed for expansion and ultimately will have eight concourses.
Arriving passengers are separated from departing passengers in Terminal 4 and its two-sided design allows for vehicle access from the east or west. Level 1, for arriving passengers, includes areas for baggage claim and ground transportation. Level 2, the departing passenger level, houses all ticket counters. Food/beverage concessions, shops and the entrances to all the concourses are on Level 3. Four levels of parking, some 3,400 spaces, top out the building.