Southwest Airlines is based out of Boston Logan Airport's Terminal B, Pier A. The airline offers passengers a simplified boarding process by using Gates 31A to 35. Although American Airlines, United, Spirit, and other major airlines share Terminal B, Southwest Airlines keeps its own separate check-in and gate sections to guarantee effective service. https://airlineterminalservice.com/southwest-airlines/southwest-airlines-bos-terminal-boston-logan-international-airport/