This logo can still be seen at airports, but the next two logos are used more often.
When this logo was first introduced, it used the Desert Gold livery. In 2001, it was changed to the Canyon Blue livery after the change from Desert Gold, to this.
In September 2014, Southwest Airlines made a major change to its logo. Not only did it introduce a new wordmark, but it was dropping the plane and was returning the heart as its main symbol which now has a yellow, red and blue striped look.