get cities

import urllib2
import re
import os.path

def major_centres(url='http://www.census.gov/popest/cities/tables/SUB-EST2009-01.csv'):
    city_map = [" ".join(x.split(",")[1].split(' ')[:-1]) for x in urllib2.urlopen(url)][4:-5]
    return [x.lower() for x in city_map]

def all_population_centres_us():
    """download census data file from http://www.census.gov/popest/cities/files/SUB-EST2009-ALL.csv -- 7M, it might take some time
    Returns list of ('city', 'state') tuples
    """
    centre_data = open('SUB-EST2009-ALL.csv', 'r')
    centre_data.readline()
    centres = []
    for k in (tuple(k.split(",")[5:7]) for k in centre_data.readlines()):
        for term in ('town', 'city'):
            if term in k[0]:
                k = (k[0].split(term)[0].strip(), k[1])
        centres.append(k)
    centre_data.close()
    return centres