The organization and function of most city tianguis are mostly the same as those in rural areas; however merchandise varies somewhat and there are problems associated with holding this type of event in the more crowded city. One of the oldest continually operating tianguis in Mexico is the one in Cuautitlán, just outside Mexico City, which has been going on every Tuesday for over 500 years. The market was established in 1491 by the Chichimecas when this area was rural and a way station between Mexico City and points north. Since then, Cuautitlan has become a crowded part of Greater Mexico City, but the tianguis is still in the same place and operated more or less in the same manner. This market congregates 7,500 vendors from various municipalities and states such as Michoacán, Puebla, Pachuca and the municipalities of northern Mexico State. It extends over 250,000 m2. There are efforts to move it away from the center and near the municipal border with Tultitlán, but the merchants have refused to be moved.