Its not that they are not popular, but that the United States is a large and expansive country with varying landscapes and extensive road networks. Electric cars are catching on but the country cant adapt as fast and effectively as smaller countries. Current electric cars dont travel too far and do not have a convenient network of ways and fallbacks to "refuel". The durability and longevity of gas and diesel powered vehicles has ruled the american expanse for decades. Itll be hard to adjust and it is happening. The United States just needs more time to adapt.
I think they do have a chance. There is someone out there that hasn't had the brilliant idea to make an awesome hybrid electric car that looks normal, is super safe, and has a small gas tank and solar power for extra back up just in case. It will happen!
Eventually, electric cars will become popular. The issues will always surround cost, and the ease of charging the vehicles. If you can plug your car in at home, and it costs the same as gas would, then the electric car market will expand. Continued advances in hybrid technology is probably the more likely scenario.
I think the current lowering of gas prices is in part a reaction toward the increasing popularity of electric cars. Environmental conscious people (who can afford it) will always go for an electric car anyway, but the rest of the population is going to go toward what is more affordable "now". So if gas prices stay within a reasonable amount, it's easier and more affordable now to stay with a gasoline-using vehicle. If gas prices rise to the point that electric cars become a more feasible financial option to the masses, then you'll see a shift. I think, however, that gas companies know they have a fine line and they are adjusting gas prices in order to keep the shift from happening.
Even though electric cars have come a long way and they provide some interesting possibilities for the transformation of the US economy, there are two major factors preventing their widespread adoption in the US. One is the lack of infrastructure: the US does not have widely distributed charging stations in the way that it has gas stations, making long distance travel difficult if not impossible. The other is less tangible, and more abstract: there is simply not a cultural inclination to adopt the electric car. Rather, we love our big, gas-guzzling vehicles, especially pick-up trucks.