Finland has a population density of 17/km^2. From a campaign, I can right now get unrestricted data at 384kbps for 3€/month, or "as much as the connection can handle", up to 14,4Mbps, typically 4Mbps, for 14€/month.
Lower population density actually helps wireless internet -- the cost is mainly not about the transmission equipment, it's about the very limited amount of total over-air bandwidth.
Lower population density actually helps wireless internet
Not quite true. Wireless internet is most cost effective when population density is at an extreme on the scale. If the density is low then you can use fewer towers that have larger cells and if the density is high then you need more capital for the higher-capacity infrastructure, but your backhauls are shorter and you have a larger userbase to recoup the investment. I would bet that for wireless operators in Finland the Helsinki area, Turku, and low-population areas make money while Kuopio is probably a break-even region at best...
The population distribution in Finland is nearly all in the lower 1/3 of the country though. Population distribution in the US is (I'm guessing) more normalized. So really you're talking about the population density of the Helsinki metro area, which is likely pretty high.
Lower population density actually helps wireless internet -- the cost is mainly not about the transmission equipment, it's about the very limited amount of total over-air bandwidth.