Construction of Vault 89 began in 2054 and finished in 2064 due to labor shortages, lack of resources, interests in other vaults, and vault size and location. The vault itself was among one of the largest vaults constructed by Vault-Tec, able to hold a maximum of 1,500 people. The residents were meant to leave after 50 years, so two G.E.C.K.s were placed inside the vault to help with rebuilding.
La Grande was one of the original sights chosen for Vault 76 to celebrate the United States' tricentennial in 2076. When the vault was finished, the title of Vault 76 would instead be given to a vault in West Virginia. As an excuse, Vault-Tec said that they remained the vault to Vault 89 to celebrate the House of Representatives forming its first quorum and electing Frederick Muhlenberg as the first speaker of the House.
La Grande residents weren't happy over this excuse, Vault-Tec said how the vault would instead commemorate George Washington being sworn in as the first president of the United States. Satisfied with this new excuse, La Grande residents allowed to vault to be debuted to the public on April 30, 2069, celebrating the 280th anniversary of George Washington's presidency and the 200th anniversary for the completion of the First Transcontinental Railroad.
Vault 89's experiment consisted of making the residents believe something, like the vault opening in 50 years, and then being lied to and told that they couldn't leave the vault to see how people reacted to being lied to and being kept over the initial wait time. The G.E.C.K.s were real however, as Vault-Tec expected the residents to successfully revolt and return to the surface, as well as to further fool the residents into believing the lie. The vault had provisions and resources to last 1,500 people for around 100 years.
The Great War
When the Great War took place on October 23, 2077, two Chinese nukes targeted the La Grande area. ICBMDF-Oregon destroyed one of the nukes, while the second hit and destroyed the Brown Military Base. Only around 1,000 of the 1,257 residents took shelter in the vault.
After 50 years of isolation, Vault 89 was scheduled to open in 2127, however, the overseer of the vault locked the main vault door and explained how he was under orders not to let anyone out until radiation levels were safe. This lead to several vault dwellers dying while rioting over the overseers actions, while the rest of the vault moved on.
23 years later, the overseer remained clear that no one was to leave until radiation died down. Not liking being kept in 23 years overtime, over 1,000 residents stormed throughout the vault, accessing the overseers room and learning that radiation levels were well under the safety threshold. The overseer was then killed for lying to the dwellers, and they left the vault for good, using it's two G.E.C.K.s to form Grande Ronde City. Using the remaining resources from the vault, the residents quickly grew Grande Ronde City into a large and prosperous settlement.