At the turn of last century the tract of Broadway between 47th and 42nd Street was the United States' preeminent theater district. While depression-era hardship later forced the conversion of many theaters into movie houses, I get the feeling that the decline of the neighborhood in the post-war era must have been driven by factors that I don't fully understand. Likewise, I'd be interested in learning how the area was able to stage a resurgence in the 1990s, rapidly returning to being a major center for shopping and entertainment.
There are a great many factors that have gone into the re-vitalization of the area known as the Theatre District in NYC; factors such as economic incentives through special tax structures and subsidies, the city's robust courting of tourist-aimed businesses, a larger police presence corresponding with efforts to reduce crime and the visibility of homelessness in the area, etc. Each of these factors are incredibly complicated to cover here and, furthermore, it's important to point out that the entire definition of what constitutes "re-vitalization" is not without controversy. But, the Theatre District certainly did see a steady growth in ticket sales, new and re-furbished theatres, as well as a surge in big-budget, tourist-driven Broadway shows that began to appear in the early 90s and that continues to today (see "The Economic Development of the 'New' Times Square and Its Impact on the Broadway Musical," by Elizabeth L. Wollman in American Music).
But, if there's one major factor in the "resurgence" (to use your term) of the Theatre District in the 1990s, it's the investment of the Disney Theatrical Group as a major producer of family-friendly musicals and their outright ownership of the New Amsterdam Theatre, which they completely refurbished in 1995. Disney and the NYC government, property developers, and other civic and private organizations worked together to bring Beauty and the Beast (the musical) to Broadway the year before as an initial experiment to test the financial viability of the venture (see "Broadway and the Beast: Disney Comes to Broadway," by Steve Nelson in TDR). With the success of Beauty and the Beast, Disney invested in the refurbishment of the New Amsterdam and produced the incredibly successful show, The Lion King. Together, these two musicals proved that a model of theatrical entertainment that was family-friendly, big-budget, and mounted with the cooperation of a major production company like Disney together with NYC government and civic partners could be financially profitable in the long term. This drew the attention of other tourist-aimed businesses, restaurants, and organizations to bring their business to the Theatre District. Americans for the Arts published an impact-survey on the larger market ramifications of a Broadway that is made up of productions financed by cooperative partnerships between entertainment production companies like the Disney Theatrical Group and NYC itself.
I tried to keep this succinct as possible, but if you'd like further clarification or other information please let know.