When a handful of armed protesters occupied a remote Oregon wildlife refuge on Sunday, most Americans probably scratched their heads. Their cause—that the government relinquish control over federal grazing lands—is not exactly a national hot-button issue.

That’s because the angry ranchers, in many ways, are living in a different world.

In most of the Northeast and South, where the only federal presence is the occasional military base or national park, complaints that the government owns too much land seem laughable.

But out west, the government lays claim to huge, state-sized swaths of land—more than 630 million acres, greater than the landmass of Texas, California, Florida and New York combined. In some states, government agencies are the biggest landowner; in Nevada, 80 percent of land is federally owned.

Data from the U.S. Geological Survey, which publishes a shapefile of federal land, makes it possible to map these areas, albeit imperfectly. Some private property may be tucked inside the boundaries of otherwise public land, USGS says.

For years, ranchers have bemoaned the government’s hold on western land, which it leases out for grazing through the Bureau of Land Management. Two years ago, when Nevada rancher Cliven Bundy made headlines after leading an armed response to a cattle round-up by federal agents, his unpaid grazing fees to BLM were at issue. (His son, Ammon Bundy, is now among the Oregon occupiers.)