Cities don't grow new people.

You can throw extra people into a city area and you can move people through it (with roads) but all the extra people die as they can't be supported (helps repel an attack though).

5.2 Tokens are square, and arc used to represent rural populations. When the term token is used, this does not include ships or cities.

Thanks for the definitive replies guys. In the Gibson version there are no roads so cities can actually become quite a barrier at times.

Grumbs

Because 'no tokens can remain in a city area' (after conflict and city building) this means that a city effectively stops population tokens from moving /though/ an area with a city in it.

That is correct. The only way to move through a city area is to get the Roadbuilding Civ card. Which aggravates Epidemic, Civil Disorder and Iconoclasm and Hersey.

For the benefit of those who don't know, Roadbulding is part of Advanced Civilization, so not really a factor here.