There are roughly 11,000 Starbucks locations in the United States, and about 14,000 McDonald's restaurants. But combined, the two chains don't come close to the number of museums in the U.S., which stands at a whopping 35,000.

So says the latest data release from the Institute of Museum and Library Services, an independent government agency that tallies the number and type of museums in this country. By their count the 35,000 active museums represent a doubling from the number estimated in the 1990s.

While most of us think of massive institutions like the Smithsonian and the Guggenheim when we think of museums, one lesson of the new data is that the majority of U.S. museums are small, nearly mom-and-pop affairs. Of the roughly 25,000 museums with income data in the file, 15,000 of them reported an annual income of less than $10,000 on their latest IRS returns.

And these museums are literally everywhere. Below, I mapped the total number of museums per county in the U.S., in both raw number and per-capita terms.

One shocker? The nation's cultural capital, at least as measured by number of museums, isn't New York, but rather Los Angeles — a city known more for Hollywood and the Hiltons than for Holbein and history. L.A. County has 681 museums compared to New York County's 414. Chicago (Cook County), San Diego and D.C. round out the rest of the top five.

But notice also that there are barely any blank counties on the map, even in sparsely populated rural areas. Storey County, Nev., population 3,942, has 11 museums, including the Comstock History Center and the Fourth Ward School Museum. Loup County, Neb., population 576, is home to the Loup County Historical Society.

The IMLS' Mamie Bittner notes that that many of these institutions, particularly in small towns and rural areas, are historical societies and history museums. "We are in love with our history — at a very grassroots level we care for the histories of our towns, villages and counties," she says. These museums may be small, but they play outsized roles when it comes to the "informal learning" that happens outside of the classroom. She added, "These museums are the community institutions that are the cornerstones of this informal learning."

Rural counties come out on top of the per-capita figures, although this is driven largely by their small populations. If we consider only counties with at least 10,000 people, San Juan County, Wash., has the greatest number of museums on a per-capita basis. I've tabulated the top 10 below.

Most museums per 100,000 residents, among counties with a population of 10,000+

County State Museums Museums per 100k residents San Juan WA 21 132.3 Marshall KS 12 120.0 Shoshone ID 15 118.2 Hancock ME 61 111.2 Nantucket MA 11 105.8 Bayfield WI 16 105.6 Baker OR 16 99.9 Franklin FL 11 94.8 Washington ME 29 90.1 Knox ME 35 88.5

The data also show where museums aren't. We've heard of food deserts, but how about cultural deserts? Up to 175 counties — home to 1.6 million people — don't contain any museums at all. Many of these are concentrated in the South, particularly Mississippi and Georgia. One word of caution here: Since the data file is culled from a variety of sources, including tax records, some of these counties may be home to museums that fell through the cracks of data collection; for instance, if they file their taxes under an office address that's different than their physical address.

If anything, the overall museum count is probably a conservative one. "Museums governed by state and municipal agencies or museums under the control of public universities may be undercounted," the researchers note.

Many institutions in the file are simply unclassifiable. There's the First State Antique Tractor Club in Greenwood, Del. The Idaho Forest Fire Museum in Moscow, Idaho. The Kansas Underground Salt Museum in Hutchinson, Kan. The Museum of Maritime Pets in Annapolis, Md. The Museum of Bad Art in Somerville, Mass. As Mamie Bittner puts it, "Anything you can dream up, there is a museum for that."