News reports on the strike that has just begun by unionized workers of the Potomac Electric Power Co. contain the customary reference that the company serves customers in the District of Columbia, suburban Maryland and a small part of Arlington, centering on Rosslyn.

Since Virginia has its own big power system, just how did Pepco get its toehold in the Old Dominion? Good question. Here's how:

Suburban Virginia, except for Alexandria, was to a surprisingly recent date, largely unsettled. It wasn't until 1937, for example, that a letter could be mailed to an Arlington address. Before that, most were addressed to R.F.D, Georgetown, D.C.

Some southern parts of Arlington and an area near Falls Church had been served by the Alexandria Lighting Co., but there were no high-voltage lines coming into Northern Virginia from the generating stations of what is now Virginia Power.

In fact, as recently as 1935, there were only 2,382 electrical customers, in all of Fairfax County, wired by the Rural Electrification Administration. And that, incredibly, was the highest total for any county in Virginia!

Rosslyn, then a scruffy but relatively dense settlement at the Virginia end of Key Bridge, needed dependable electric power. So did Fort Myer and, later, the Pentagon. Pepco was willing and able to provide it. So it got the franchise, which remains to this day.