Los Angeles International Airport officials on Tuesday announced a massive airline relocation plan for May involving 21 airlines moving to different terminals or to different locations within terminals.

The relocations are being triggered by Delta Air Lines’ $1.9 billion expansion project at LAX that involves moving from Terminals 5 and 6 to Terminals 2 and 3 and a complete makeover of Terminal 3. That move is setting off a chain reaction of other moves as most of the airlines currently in Terminals 2 and 3 must find other homes.

Related Link: Delta to Lead 24 Airline Relocations to New Terminals at LAX

The relocations will take place over five days from May 12 through May 16, with the bulk of the moves taking place on the nights of May 12, May 14 and May 16.

“Delta’s move is one more element of LAX’s massive modernization effort which continues the transformation of the airport and will improve the guest experience,” Los Angeles World Airports Commission President Sean Burton said in a statement. “While moving 21 airlines over three nights is a monumental task, Delta and the LAWA team have been planning and preparing for months to ensure a smooth transition.”

Los Angeles World Airports Chief Executive Deborah Flint said the aim is to improve the efficiency of air carrier operations and to make connecting to flights easier for travelers. “The immediate result is more efficient airline operations amongst partner carriers and facility improvements that will be made in Terminals 2 and 3,” she said in a statement.

Public policy and energy reporter Howard Fine can be reached at [email protected]. Follow him on Twitter @howardafine.