Correct me if I'm wrong but 'DC' is terrible at long distances, you lose vast amounts of the energy put in to push it the whole way. This is why AC is used today.
Consider this your correction. With modern technologies, High Voltage DC is actually the preferred method for long-distance power transmission. In the past, the issue was always the AC/DC conversion at either end of the line.
HVDC has a number of things to recommend it.
1) Uses the entirety of the conductor for power transmission. When you push AC through a conductor, it exhibits what's called the "Skin Effect." In the case of 60Hz AC, the power is actually only using about the outer 7mm of the conductor. Power companies actually do make use of this, using a steel core for tensile strength, and a copper sheath for high conductivity, but it also puts a limit on how much current a given conductor can actually carry. At DC, the power will flow through the entirety of the conductor, and since resistance is proportional to the cross-section area of the conductor, you get less loss for a given piece of cable.
2) AC loses significant amounts of power to the ground through capacitive losses. In effect, the transmission line forms a very large capacitor with the earth. For long transmission lines this becomes a significant effect. Again, because this is due to frequency, DC solves the problem.
3) Isolates and relaxes the frequency requirements of the grid. After they lost most of the power grid to an ice storm in 1998, Quebec Hydro rebuilt their grid using HVDC transmission lines and interconnects to the eastern grid. Because of this, they were isolated from the frequency instability that caused the large north-east blackout in 2003 and thus the lights stayed on.
Anyhow, the main reason why AC has been used for long haul transmission is because when the grid was built out, there was no efficient way to convert power between AC and DC or to change the voltage once it was in the DC domain. With the advent of modern power electronics, it's quite possible to build megawatt and/or gigawatt scale inverter/rectifiers that will do this more efficiently than the AC losses for long distance power transmission. As with all of our crumbling infrastructure, the main problem is that no one is willing to invest in the capital expenditures to make it happen.