If you think 15 blocks is walking distance; this sign is at a tiny gas station next to the Watergate apartment building at the intersection of Virginia Avenue, NW and Rock Creek Parkway (I drive by this place frequently; this gas station has always been $1 per gallon higher than anyone else in the area).
Don’t know the area. Did not write the article, but it was in The Weekly Standard with that title.
Use of block size, is a very inaccurate method to describe distance. There is no real standard between cities. Grid pattern issue make it worse.
I suspect that 15 blocks is the nearest gas station to the White House. Also bet the regulation of such installations near the White House makes it very costly.