We know of several cultures that urbanized in pre-Columbian North America, but most of these cities and cultures have been in the south. In particular, we have the Aztecs and Tenochtitlan, the remains of the Mayan urban culture, and the Incan cities of the Andes, but I find myself at a loss when I try to identify any known cities, if they existed in the region we now call the US and Canada.
Where there any large urban agglomerations that occurred, like say with the Mississipian or Hopewell?
There's always room for discussion, but perhaps the section Cities and Monumental Architecture in our FAQ will answer your inquiry.