Global T-Virus pandemic (DeCandido)

Despite the Raccoon City survivors' best efforts to expose the truth, Umbrella managed to cover up the incident by stating the destruction of the city was the result of a nuclear meltdown at a power station. But they had made a fatal oversight. A single scientist, Dr. Jim Knable, had been unknowingly infected, and transported to San Francisco. He soon succumbed to the virus' effects and began infecting others. Attempts were made to confine the outbreak to the Mission District, but it was already too late. Unsuspecting carriers had already boarded aeroplanes, and by the time the President of the United States was briefed on the nature of T-Virus, there were already carriers inside the White House itself.

At the suggestion of his science division head, Dr. Sam Isaacs and Umbrella Chairman Albert Wesker began moving corporation assets to the various underground facilities maintained throughout the world. The corporation would soon become the only remaining entity with the ability to effectively defend itself against victims of it's virus. It wasn't long before the rest of planet suffered the same fate as the United States.

A convention center in Baltimore, turned into a safe haven by Jill Valentine, is an example of a city haven for humans. It became a home to more than a hundred humans who managed to make a living among the ruins.