A number of their World Cup players, including Wayne Rooney, Juan Mata, David de Gea and Shinji Kagawa, as well as new signings Luke Shaw and Ander Herrera, will also depart for the United States on July 18.
In Van Gaal's case, that could be just five days after his involvement at the World Cup in Brazil ends.
The Dutchman is due to take charge at Old Trafford as soon as his commitments with the Holland national side are over.
Holland have reached the World Cup semi-finals in Brazil and hope to be involved in Sunday's final in Rio
Even if they lose they will still be playing on Saturday in the third-place play-off.
Rooney's participation in the World Cup, along with the other England players, came to an end on June 24.
It means they will have had less than four weeks off before beginning pre-season preparations, but their presence will be a boost for Van Gaal as he begins work immediately.
Holland striker Robin van Persie is not expected to link up with the squad until August.
United play Los Angeles Galaxy on July 23 before games in the International Champions Cup against Roma, Inter Milan and Real Madrid.
Should they reach the final of that competition - which also features rivals Liverpool and Manchester City - they would play in Miami on August 4.
A United statement read: "Fresh from his exploits at the 2014 FIFA World Cup, new manager Louis van Gaal will be part of the full tour with his first match in charge of United taking place against LA Galaxy in the Chevrolet Cup at the Rose Bowl on Wednesday, July 23
"Many of United's World Cup players will also be in attendance for the duration of the tour including Wayne Rooney, David de Gea, Shinji Kagawa and Juan Mata.
"As well as the return of familiar faces, new signings Ander Herrera and Luke Shaw will also be part of the travelling squad to make their Manchester United debuts."
Source : PA
Source: PA