The short answer to this is that natives in North America (which actually extends all the way to Panama -- you seem to be using it to refer just to the US and Canada) did urbanize, but many of their larger cities were depopulated by disease, slavery and other deleterious happenings before the first English settlements started being established on the east coast of what's now the United States.

The Pueblo Tribes, for example, established settlements, some of which date back to the 12th century and are still inhabited; although they were affected significantly by Spanish enslavers raiding their communities, the Pueblo Tribes were able to effectively resist the colonizers for decades and threw them out of their territory completely in 1680.

The largest Native urban center in what's now the US was the town now called Cahokia, east of what's modern-day St. Louis. From its founding around the year 650, it grew steadily until its peak around 1100, when it's estimated to have had between 14,000-18,000 inhabitants.

Plenty more to be said here, but I'll point you toward the actual experts who have contributed answers for our FAQ.

There was a similar question asked a bit earlier today, that currently has several links that you might find informative.