Late last month, for the 32nd year in a row, Banned Books Week was marked across the US. Spearheaded by the American Library Association’s (ALA) Office for Intellectual Freedom, the annual salute to the freedom to read has become a fixture. It aims to counterbalance perennial challenges to the content of books and efforts to get them banned, usually from schools and libraries.

The ALA collects information on which books are objected to and reports on prominent recurring themes that tend to generate moral or ideological indignation. Subjects such as religion, race, gender, sexuality and allegations of sexually explicit content or offensive language frequently top the list.

More worrying, however, is the recent rise in efforts to get books banned that cover poverty and social class. At a time when rising inequality and the demonisation of poorer people (both in the UK and the US) is commonplace, such attempts to remove books that depict the reality of life for people who are struggling should concern us all.

Numerous studies have shown that reading about people, issues or circumstances unfamiliar to us can engender empathy – in times of acute social and economic divisions this becomes all the more important. It is not just wealth that separates rich and poor, but ignorance and the absence of social contact.

The US has a longstanding tradition of books being challenged on sometimes spurious grounds (often, but not always from the conservative right) even while the first amendment of the constitution protects “access to ideas as well as free speech”. There are numerous organisations, including the ALA and National Coalition Against Censorship (NCAC) that contest such moves, still, there’s something unsettling about the recent manifestation of complaints on socio-economic grounds.

Deborah Caldwell-Stone, deputy director of ALA, says: “We have seen challenges to books where the content [probes] received wisdom on issues like poverty and class or offers an alternative political view point on a situation.” Authors such as Toni Morrison are continually targeted, she points out, because they are “writing about concerns related to race and class ... often unflinchingly portraying what African Americans have suffered in [the US].” Most books challenged are fiction but increasingly non-fiction works “that address diverse topics … or raise issues of class and the economic environment,” are also being contested she says.

A frequent complaint, according to Joan Bertin, executive director of the NCAC, is of books being “anti-capitalist”. She says this is conflated by some sectors of society as somehow undermining American or Christian values. Among the most high-profile books challenged lately was bestselling author David K Shipler’s The Working Poor: Invisible in America, targeted by a group of parents in Texas during Banned Books Week, and Barbara Ehrenreich’s Nickle and Dimed: On (not) Getting by in America, which explores the challenges of low income and refutes the myths around poverty and supposed fecklessness. One of the many objections levelled at Ehreneich’s book was in 2011 when a parent argued that it promoted “economic fallacies and socialist ideas”.

Some of the latest objections have been directed at works exploring topics such as social unrest. Following months of controversy, hundreds of students in Denver, Colorado have been walking out of classes in protest against proposals by some people that teaching materials on an advanced history course should actively promote “the benefits of the free enterprise system” and “not condone civil disorder [or] social strife”.

Challenges to books that unmask societal fissures along economic and class lines are a symptom of wider woes and rising tensions around inequality, low wages, poverty and insecurity. Ensuring that literature addressing these issues remains freely available is a worthy cause in pursuit of social justice.