With a fleet of more than 700 aircraft, Southwest Airlines is the world’s largest operator of the Boeing 737.

Since Southwest began scheduled passenger service in 1971, the 737 has been a staple for the airline. While most of the Southwest aircraft you see are painted in vibrant colors of either the older “Canyon Blue” or newer “Heart” liveries, travelers might also notice one of the more unique paint schemes Southwest features on a few of its “state livery” aircraft.

As part of Southwest’s 20th anniversary in 1991, the Dallas-based airline unveiled “Lone Star One,” its first state livery on a Boeing 737-300 aircraft. The state flag of Texas was colorfully painted on the entire fuselage, and the bulkhead next to the plane’s boarding door featured the words “Lone Star.”

Why did Southwest choose to feature Texas in its first state livery aircraft? Along with being headquartered in Dallas, the airline’s first three routes consisted of a triangle serving Dallas, Houston and San Antonio.

The addition of “Lone Star One” 28 years ago launched a tradition for Southwest that still stands – today, Southwest has 12 aircraft in its fleet that honor the states that have played a role in the airline’s history, according to Southwest Airlines spokesman Brian Parrish.

“The liveries are a visual representation of our gratitude for the support shown to Southwest over the decades by the customers and employees from each of the states represented,” said Parrish. “Southwest customers love flying on the liveries from their home state, and our employees take great pride in the specialty designs.”

In November 1994, Southwest unveiled its second state livery plane, “Arizona One.” Painted on another 737-300 aircraft, the livery commemorated the airline’s growing presence at Phoenix Sky Harbor International Airport. One year later, “California One” joined Southwest’s fleet as the third state livery aircraft.

As the airline continued to expand and introduced the Boeing 737-700 series to its fleet in 1997, Southwest went on to paint more state liveries on its aircraft. However, in September 2017, Southwest officially phased out the rest of its 737-300 fleet after operating the aircraft model for 33 years.

With the retirement of the 737-300 came the retirement of the original state planes of Texas, Arizona and California. To return the missing state liveries from its fleet, the company pulled aside three newer Boeing 737-700 aircraft that were due for new coats of paint. After nearly two weeks of being stripped down and re-painted, each aircraft re-entered service adorning the colors of the three original states, carrying on the tradition to this day.

In March 2018, Southwest revealed its latest state livery – “Louisiana One.” Painted on a 737-700 aircraft, the 12^th state livery in the airline’s fleet commemorated Southwest’s 30th year of serving New Orleans’ Louis Armstrong International Airport.

Southwest is currently the only airline that paints specialty aircraft adorning the colors of states’ flags. However, U.S. Airways, which ceased operations and merged with American Airlines in 2015, carried out a similar tradition.

Following U.S. Airways’ merger with America West in 2005, the former airline painted two Airbus A319s wearing the state flags of Nevada and Arizona, in honor of inheriting America West’s two hubs – Phoenix and Las Vegas.

In addition to state liveries, Southwest also has three specialty aircraft. Two Boeing 737-700s are painted in a metallic gold scheme honoring the airline’s co-founder Herb Kelleher, who died in January 2019, and former president Colleen Barrett.

A third special scheme named “Triple Crown One” is dedicated to employees who helped Southwest receive recognition from the Department of Transportation (DOT) for what the airline calls the “Triple Crown” of awards. For five consecutive years, Southwest was rated No.1 by the DOT in three categories: baggage handling, customer service and on-time performance. Originally painted on a 737-300 in June 1997, the livery was transferred over to a newer -700 model in May 2015.

Other airlines including American, United Airlines and Condor, have special “throwback” liveries in their fleet. Read more here.