BTW, there are all kinds of mapping data sets out there for free that you could use as your base. They are already vectorized and could be converted to illustrator files. For example, this one is US census districts:
http://data.geocomm.com/readme/usgs/atlas/html/censusmt.html
You can open the table (link that says download table) in excel and see the list of polygons. That one has 3194 of them for the country.
You can also download a free GIS viewer that will let you look at the data itself:
http://www.esri.com/software/arcgis/explorer/index.html
I'm not sure if it allows for exporting to ai files, but if not I could do that for you (just make sure you know you want to use that data set so it is a limited number of requests).
Anyway, using vector data out there saves a lot of time over trying to vectorize a map with a background on it.