I'm in the northeast and have a basement sump with a few hundred gallons. I used a dehumidifier to keep humidity in check. I know they're not very popular in this crowd. The upside is that they're fairly cheap, very available and do the job well. The downside is they're loud(ish), produce heat and suck up a lot of energy (mine uses almost 600 watts). I only have to run mine part time to keep humidity around 50%. Noise and heat isn't an issue since my basement stays around 70 degrees even in the summer. The energy comsumption sucks, but it would be the same for an AC unit (and then I'd be cooling the area too much and my heaters would be working harder).
Ron