Though the majority of the country has access to cable television, broadband internet, and other forms of mass communication, there are still areas where significant percentages of the population get their TV "over the air" — which is to say they pull in signals with an antenna. (Almost all of us still do this with radio.)
When I spoke with PBS's CEO Paula Kerger in 2016 (before the election), she explained to me how expensive it can be to operate TV stations in those areas:
There are people that just assume that cable television or satellite are how most people get content. That's just not taking into account that there are parts of the country, particularly in rural areas, where over-the-air broadcast is significant in terms of how we get our content to people. But it's also how we connect into a lot of cable systems — through over-the-air broadcasts. [Cable companies] will pull down an [over-the-air] transmission, then send that out.
There are some in our system that would love nothing more than to not have to bear the cost of over-the-air transmission, the cost of the equipment and everything. I think it is such a significant part of our audience that it is the cost of doing business. Being able to maintain that is important.
The costs associated with over-the-air broadcasting are usually associated with the equipment needed to transmit said broadcasting — think of the giant TV and radio towers that still stand in many of the country's most isolated areas. These costs are significant, and infrastructure upkeep is a major part of local broadcasting budgets.
A CBS or ABC affiliate can make money by selling local advertising to cover those costs. But PBS affiliates don't sell ads, which means they need to make up that money somewhere. In urban areas — where there's a longer-lasting tradition of various forms of patronage for arts and culture (to say nothing of far more people to donate cash) — that's less of a problem. But in rural areas, the CPB is the difference between life and death for many stations.
And local PBS and NPR affiliates in rural areas are occasionally among the only local stations left. Much of the country's radio infrastructure has been bought up by one corporation (iHeartRadio), while other local TV stations are generally affiliated with one of the major, national networks.
To be sure, PBS and NPR stations still broadcast other PBS and NPR programming, but they're also far more likely to air, say, a talk show about local affairs, a local gardening program, or some other sort of programming deliberately aimed at one community in particular. It's a part of the mandate of individual stations, and both broadcasters as a whole. This is exceedingly rare in a country where more and more media organizations are part of large, corporate monoliths operated out of New York, Los Angeles, or Washington, DC.
Kerger more thoroughly explains how PBS in particular is subtly different from, say, the broadcast networks in my full interview with her. Briefly, most networks are dictated in a top-down fashion — ABC makes almost all the decisions about what your local ABC affiliate will air in most major time slots — but PBS is more bottom-up. Its affiliates have much more leeway in making programming decisions, and PBS itself is less a direct broadcaster than a collective of its member stations. (That's why anytime you read something about PBS programming that's written by a national news outlet, you're usually advised to "check your local listings" for airtimes.)
And PBS is still the home of some great programming, from its various British drama imports to long-running, venerable documentary franchises like American Experience, American Masters, Nature, and Nova. It's also the home of the work of Ken Burns, perhaps the best-known documentary filmmaker in America, and Independent Lens, still one of the best distribution platforms for independent films in existence nationwide. That doesn't even touch on NPR, which backs a wide variety of news programming at both national and local levels.
Rural areas turned out in droves to vote for Trump in November 2016. And while the fact that the American Health Care Act will place an undue burden on Trump voters is of more immediate importance than whether Trump's proposed budget, if passed, will cut off those voters' access to PBS, the budget is another example of how Trump's policies often place his supporters at a disadvantage.