YOSEMITE WEST, Calif. — THE limit of John Boehner’s reach is defined by a line of orange traffic cones and a forest green and white S.U.V. that’s parked, lights flashing, beneath a stand of ponderosa pines on the edge of a scenic meadow in Yosemite Valley. Directly overhead lies the southeast face of El Capitan, also known as the Dawn Wall — a monolith of cleaved gray granite rising more than 2,800 feet that is, for legions of rock climbers around the world, without peer.

An amiable young ranger wearing a fleece winter hat leans forward as you roll to a stop. “I’m sorry, park’s closed,” he says with an apologetic shrug.

The fact is, our national parks are not isolated boundaries within our country, but porous lands intricately woven into the fabric of a multitude of communities. Yosemite is bisected by Routes 41 and 120 and has two significant communities of private development — Foresta and Yosemite West — that are accessible only from the park. Consequently, the major roads must remain open, while a furloughed army of rangers, tour guides, hospitality staff members and maintenance workers remains in the park. For many, the reason in choosing their jobs was where they got to work. For a handful, the reason was rock climbing.

If you happen to have a P.O. box in ZIP code 95389, which serves Yosemite Valley, as some of my friends do, the young ranger, one of the few still working, is obliged to let you pass, and you may execute a hard right-hand turn around the traffic cones and pull back onto the Yosemite loop road. In Camp Curry, where families normally throng for ice cream bars and pizza, it’s quiet and empty except for white government vehicles and a few idle figures.