[Hendog]

I'm trying to understand how it is that AC has less loss vs DC when transmitted over long distances. I've Googled it and found some statements such as this one:

"When A.C. is supplied at higher voltages in long-distance transmission, the line losses are small compared to a D.C. transmission."

It's not clear whether they are making the comparison at the same voltages for each. I would think the resistance of the line would be the same for any current regardless of the voltage being AC or DC, no? The only thing I can think of that would make the difference is that AC, for lack of a better term, rides over the surface of the conductor.

I know it's easier to step up and step down the voltages via transformers in AC, but besides that, all things being equal, let's say at a given voltage of 120 volts AC and also DC, does AC actually travel more efficiently over the same line than does DC? Or is it that the advantage is only achieved at higher voltages, say 70,000 Volts?

I'm missing something here. Maybe the answer requires a level of math beyond my grasp, but I'm hoping the brain trust here will have the answer(s) in laymans terms I would understand.