Based on the text, please give me a brief summary of the history of the DTES neighbourhood in Vancouver
The DTES has transformed from the focal point of Vancouver’s cultural and commercial life at the start of the 20th Century to an impoverished neighbourhood with many socio-economic problems by the 1980s. Since the 1990s, the DTES has been home to a public health emergency due to drug overdoses, HIV infection, a housing crisis, and mental health problems.