Airlines continually tweak the order in which they board passengers. They’ve tried everything from a “free for all” to window seats and back of plane first, to random boarding. One airline has even tried boarding passengers without carry-on bags first, which makes sense since pausing to find overhead bin space jams up the boarding of everyone behind. Jetblue recently changed its boarding procedure, so it’s a good time to take a look at how the different U.S.-based airlines are getting bums in seats.

Why is this an issue? Overhead bin space. If you’re the last to board, then the chances increase that cabin crew will make you gate-check your carry-on bag if the bins are filled by those who boarded ahead of you.

Alaska 

Pre-boarding: Military, special needs, families with young children

First group: First class

Second group: Mileage Plan elites, anyone purchasing premium class seating

Third group: Passengers sitting behind exit rows

Fourth group: Everyone else

American 

Pre-boarding: Concierge key members. Families with small children may pre-board upon request; see gate agent

First group: First class; Active duty U.S. military with military I.D.; Business Class on a 2-class international aircraft

Second group: Executive Platinum; oneworld Emerald; Business Class on a 3-class aircraft

Third group: Platinum Pro; Platinum; oneworld Sapphire

Fourth group: Gold; oneworld Ruby; Alaska Airlines MVP members; AirPass; Premium Economy; Citi AAdvantage Executive card members; customers who bought Priority boarding

Fifth group: Main Cabin Extra; Eligible AAdvantage credit cardmembers; eligible corporate travelers

Sixth group: Main cabin

Seventh group: Main cabin

Eighth group: Main cabin

Ninth group: Premium economy

Delta 

Pre-boarding: Customers needing assistance or additional time to board, including families with car seats or strollers

First group: Delta One customers; First Class customers; Diamond Medallion Members

Second group: Platinum Medallion Members; Gold Medallion Members; Delta Comfort customers; Flying Blue Platinum and Gold members; Virgin Atlantic Flying Club Gold members; Virgin Australia Platinum and Gold members; GOL Smiles Diamond members; SkyTeam Elite Plus members

Third group: Silver Medallion Members; Delta Corporate Travelers; Priority Boarding Trip Extra customers; Gold, Platinum and Reserve Delta SkyMiles Credit Card Members; Flying Blue Silver members; Virgin Australia Velocity Silver members; GOL Smiles Gold members; Sky Team Elite; Crossover Rewards SPG Platinum members

Fourth group: Main cabin

Fifth group: Basic Economy Passengers (E); main cabin passengers booked in T, X and V fares

Frontier 

Pre-boarding: Those needing special services, families with young children

First group: Passengers purchasing a carry-on bag fee; “The Works” passengers; elite frequent fliers

Second group: everyone else

JetBlue 

Pre-boarding: Passengers with disabilities

First group: Mosaic frequent fliers; Mint (first class)

Second group: Passengers buying “even more space” seats

Third group: Active military and passengers with children in car seats or strollers

Fourth group: JetBlue calls the next group “C”. Although logic would suggest that these passengers are seated at the back of the plane in window seats, a jetBlue spokesperson says that, “The exact group is determined upon check-in and takes a number of factors into consideration.” Anecdotally, passengers have said that window seats are boarded first.

Fifth group: Group D

JetBlue doesn’t specify exactly which passengers are assigned to this group

Sixth group: Group E

JetBlue doesn’t specify exactly which passengers are assigned to this group

Southwest 

Pre-boarding: Customers who have a specific seating need to accommodate their disability or need assistance in boarding the aircraft or stowing an assistive device. Customers who are traveling with assistance and emotional support animals qualify.

First group: Passengers with and “A” group boarding pass and customers on “business select” fares

Second group: Passengers traveling with a child 6 or younger

Third group: Active military

Fourth group: Those with a “B” group boarding pass

Fifth group: Passengers with a “C” group boarding pass

Spirit 

Pre-boarding: Unaccompanied minors, passengers needing extra time to board.

First group: Passengers in the “Big Front Seat” section.

Second group: Holders of the Spirit MasterCard; passengers who buy “Shortcut Boarding” for a fee or who have paid for a carry-on bag

Third group: Passengers sitting in rows at the rear of the plane

Fourth group: everyone else

United 

Pre-boarding: Unaccompanied minors; customers with disabilities; uniformed members of the U.S. military; families traveling with children age 2 and younger; United Global Services members

First group: Premier 1K; Premier Platinum; Premium cabins: United Polaris first class, United Polaris business class, United First and United Business

Second group: Premier Gold; Star Alliance Gold; Premier Silver; Star Alliance Silver; customers who have purchased Premier Access; United MileagePlus Explorer, Club, Presidential Plus and Awards Cardmembers

Third group: Economy plus

Fourth group: Economy

Fifth group: Basic Economy