By The mid-2070s, the Great war was reaching its peak. The United States sought ways to try to preserve the population in case of nuclear Armageddon. The solution was Vaults, an idea of Vault-Tec, to build underground shelters to preserve the American population. Unfortunately, the United States didn’t have enough money to build 400,000 Vaults, each with a bit over a thousand occupants. So by the time of the Great War, At least 122 vaults were built and finished. The Vault was sealed on October 21 2077, two days before the bombs fell.