grid.py

def xxrange(start, stop, step=1):
    cur = start
    while cur < stop:
        yield cur
        cur += step

locs = reversed([(lat, lng) for lat in xxrange(18.0, 64.0, 0.1) \
    for lng in xxrange(-124.0, -66.0, 0.1) if lat is not lng])

for i, loc in enumerate(locs):                                                  
    print i, loc