L’Enfant laid Washington out on a grid skewed by long diagonal avenues — Connecticut, Massachusetts, Pennsylvania — and planted them with elms, plane trees, and lindens. The result, accidentally or not, is that downtown DC has more continuous tree-shaded sidewalk than any other American capital. The avenues do the work. The numbered and lettered streets are almost an afterthought.
These picks all start from the K Street corridor, where most of the law-firm and lobby-shop offices sit, and end at a lunch spot reachable in under fifteen minutes. Each one stays on an avenue for as much of the walk as possible. The shade scores account for the canopy — DC’s tree cover is real and accurately mapped — and for the building line on the east-facing side of each avenue, which matters more in August than people think.