Recently, I wrote about public education in crisis. But two other vital public services are also being hit hard by budget cuts: mental health care and assistance to the homeless.

Education is at least partly buttressed by the fact that almost everybody supports the idea of public schools. Cuts generally provoke an outcry, and politicians often pledge to do their best to restore funding as soon as the economy improves. Mental health and homelessness services, by contrast, are in some ways more vulnerable over the long-run: the constituencies they serve tend to be perceived by much of the public as nuisances at best, as societal menaces at worst; services to these groups tend to be costly; and the success rates (illnesses controlled, homeless folks moved into permanent housing) are, while a whole lot better than nothing, sometimes mediocre. And so, as local and state government budget crunches worsen, it's no surprise many of these services are on the chopping block. The Centre on Budget and Policy Priorities (CBPP) reports that Connecticut's governor has proposed suspending all state-funded homeless services for the rest of the fiscal year; California has eliminated funding for domestic violence shelters; Massachusetts has reduced spending on geriatric mental health services; Ohio has, according to the CBPP report "eliminated virtually all state funding for mental health treatment for individuals who are not eligible for the state's Medicaid programme"; while Virginia has reduced the amount it pays hospitals to treat people with mental health or substance abuse issues and slashed its grants to local mental health service providers.

In fact, search online for mental health cuts by state, and it rapidly becomes clear that across America the already-fragile community mental health service infrastructure is being battered. The impacts are by no means abstract. Community mental health clinics provide not just medicines and counselling services, but an array of other support: they help the mentally ill find housing and jobs; and they work with them to navigate complex government bureaucracies and access benefits. They provide friendship to people who are frequently lonely, depressed and marginalised from the broader community. Cuts to the mental health infrastructure in Kansas have resulted in a documented increase in calls to suicide hotlines and rising numbers of people being admitted to psychiatric hospitals in a psychotic state. Communities like Santa Barbara, California, have seen homelessness spike at least in part because broke local mental health services are having to turn sick men and women away.

And, once homeless, the mentally ill – as well as the non-mentally ill homeless – face a similar scramble for scarce resources. Tens of millions of dollars have been removed from city shelters in Washington DC, the nation's capital. As winter set in last November in Minnesota, one of the coldest states in America, thousands of low-income families lost emergency financial assistance to help pay rent to avoid being evicted. The National Coalition for the Homeless estimates more than 700 homeless Americans die of hypothermia each year – and with homeless services being slashed, that number will likely increase in the years to come.

Meanwhile, New York City is considering closing the largest homeless drop-in centre in Manhattan. Activists worry that homeless residents with drug addictions, HIV, tuberculosis, or mental illnesses will find it harder to access treatment if they aren't in stable housing situations. And that, ultimately, could trigger a broader public health problem.

In cities, counties, and states across America, homeless and mental health services are being eviscerated. As a result, programmes that have been carefully built up over decades are going to close. With them will go the expertise of trained staff; the accumulated experience of caseworkers who have gotten to know the needs and behaviours of individual clients, and who might have spent years getting those individuals to trust them enough to let them provide help; and the fragile bonds, the sense of belonging, that in some instances are the only things keeping a person on the edge from spiralling into more serious illness and more intractable long-term homelessness.

There are no easy answers here: too many branches of government have simply run out of cash and of quick-fix solutions. Without more support for these programmes from the federal government, or local ballot measures that earmark funds for particular social services, it's inevitable that many of them will be cut in the next few years.

But, at the very least, this merits a frank conversation, an acknowledgment that the risks associated with dismantling this infrastructure are huge: tear down services to these groups during the down times and there is just no guarantee that a political consensus will emerge at the back end of the fiscal crisis to restore such services. After all, homeless people or the seriously mentally ill don't tend to have much of a political voice. Their needs are, too often, seen as irrelevant.

The undermining of these vital social services will have an impact that long outlives the current economic crisis. Nothing would more forcefully illustrate the phrase "private affluence and public squalor", coined by progressive economist John Kenneth Galbraith, than a booming America, its landscape littered by ever more homeless encampments, ever greater numbers of untreated mentally ill people and, in consequence, a growing sense that, for the affluent majority, public spaces are unsafe and unseemly. That happened in Victorian England; it occurred again in both America and the UK in the 1980s. It would be a great tragedy to let the 2010s and 2020s witness a repeat performance.