The Holyoke Range, a relatively small mountain range in western Massachusetts, USA, which separates the Pioneer Valley from the Springfield metropolitan area.
This name reflects the juxtaposition of the areas to the north and south of the range. The relative wealth, educational level, smugness and quality of life of Northampton and Amherst, Massachusetts to the north - and the urban decay, teen pregnancy, street violence, drug use, and poverty of Holyoke, Chicopee, and Springfield Massachusetts, a mere ten miles to the south.
A Tofu Curtain may exist in other areas, such as Princeton, New Jersey and New Haven, Connecticut (home to Princeton and Yale Universities, respectively). However, this is the most dramatic example of a physical barrier which approximates the socioeconomic divide.
Northampton is a happy liberal utopia. If you want a teen hooker and an 8 ball, you should cross the Tofu Curtain and go to Holyoke.