Local Vocabularies, Divergent Catalogs: The Growing Movement to Rewrite LCSH from the Ground Up

For decades, the Library of Congress Subject Headings system has functioned as the common language of American library cataloging—a shared vocabulary that, whatever its limitations, allowed catalogs across thousands of institutions to speak to one another. That shared language is showing signs of fragmentation. Not a dramatic rupture, but a slow, deliberate divergence, driven by institutions that have concluded that LCSH, as currently constituted, cannot adequately describe their collections or serve their communities.

The institutions doing this work are varied in size, mission, and approach. Some are large research universities with the technical infrastructure to maintain parallel controlled vocabularies. Others are small tribal archives operating on minimal budgets, hand-building terminology that reflects Indigenous knowledge frameworks LCSH has never accommodated. What unites them is a shared conviction: that the cost of cataloging conformity, measured in the communities and materials that standard headings render invisible, has become too high.

Why Institutions Are Pushing Back

The critiques of LCSH that motivate local vocabulary development are not new. Scholars and practitioners have documented the system's Eurocentric assumptions, its historically pejorative or dismissive terminology for marginalized communities, and its tendency to treat non-Western knowledge traditions as subcategories of Western disciplinary frameworks. What is newer is the institutional willingness to act on those critiques rather than simply document them.

The momentum has been building for several years. High-profile advocacy efforts—including the sustained campaign that eventually led the Library of Congress to replace the heading Illegal aliens with Noncitizens and Unauthorized immigration in 2016—demonstrated both that change was possible and that it required sustained external pressure. For some institutions, that lesson cut in two directions: it showed that LCSH could be revised, but also that revision moved slowly and was subject to political interference. The 2016 change was initially approved, then reversed under congressional pressure, before eventually being reinstated years later. That episode clarified for many catalogers that waiting for the Library of Congress to solve representation problems was not a reliable strategy.

What Institutions Are Actually Building

The range of local vocabulary projects underway across the United States reflects the diversity of the communities driving them.

Some of the most systematically developed alternatives have emerged from tribal colleges and Indigenous archives. The Protocols for Native American Archival Materials, developed through a collaboration involving tribal communities and archivists, articulates principles for describing Indigenous collections that diverge substantially from standard LCSH practice. Several institutions have translated those principles into working controlled vocabularies—locally maintained term lists that replace or supplement LCSH headings for materials related to specific tribal nations, ceremonial practices, and Indigenous ecological knowledge.

At the other end of the institutional spectrum, large academic libraries have developed what catalogers sometimes call local heading add-ons: formally maintained supplementary headings that are applied alongside LCSH terms to provide granularity or specificity that the standard system does not offer. A university with a major collection in Latinx studies, for instance, might maintain local headings that distinguish among national-origin communities that LCSH groups under a single, flattened term.

Public libraries in communities with significant immigrant populations have pursued similar strategies, sometimes in coordination with local cultural organizations, to develop subject access in languages and conceptual frameworks that LCSH's English-language, Western-centric structure does not support.

The Technology That Makes Divergence Possible

It is worth noting that the current wave of local vocabulary development has been enabled, in part, by changes in library technology. Legacy integrated library systems made maintaining local heading files technically cumbersome and cataloging-staff-intensive. Modern library services platforms, combined with the growing availability of linked data infrastructure, have substantially lowered the technical barriers to maintaining parallel or supplementary controlled vocabularies.

The linked data movement, in particular, has provided both a conceptual framework and a set of practical tools for institutions that want to maintain local terminological control while preserving the ability to share and exchange catalog data. In a linked data environment, a local heading can be explicitly related to—but distinguished from—a corresponding LCSH term, allowing institutions to serve their own communities without entirely severing connections to the broader bibliographic universe.

This is not a solved problem. Interoperability between locally maintained vocabularies and national authority files remains technically and procedurally complex. But the trajectory is toward greater feasibility, not less, and institutions that have invested in linked data infrastructure are finding that local vocabulary maintenance is increasingly tractable.

The Fragmentation Question

The growth of local vocabulary projects has prompted genuine concern among cataloging professionals about the long-term implications for shared catalog infrastructure. The value of a common controlled vocabulary is, in significant part, a network effect: it enables resource sharing, interlibrary loan, union catalog searching, and the aggregation of holdings data across institutions. Every degree of local divergence from standard LCSH reduces that interoperability, at least at the margins.

Critics of the localization trend argue that the solution to LCSH's representation problems is reform of the central system, not proliferation of local alternatives. They point to mechanisms that already exist for proposing new or revised headings—the Subject Authority Cooperative Program (SACO) allows any participating institution to submit heading proposals to the Library of Congress—and argue that those mechanisms, however imperfect, represent the appropriate channel for systemic change.

That argument has real force, but it runs into the practical reality that SACO proposals take time, require institutional membership and staff capacity, and are not guaranteed to succeed. For a small tribal archive with urgent descriptive needs and limited cataloging staff, waiting years for a heading proposal to work its way through the authority control process is not a viable option.

A Spectrum, Not a Binary

The most intellectually honest framing of the local vocabulary movement is probably not as a choice between conformity and rebellion, but as a spectrum of responses to a system that was not designed with every community in mind.

At one end of that spectrum are institutions making modest, carefully documented local additions to LCSH—supplementary headings that extend rather than replace the standard vocabulary, maintained in ways that preserve interoperability. At the other end are institutions that have concluded that LCSH is so inadequate for their materials that building a parallel system from scratch is the only responsible course.

Most institutions engaged in this work occupy the middle of that spectrum, navigating pragmatically between the need to serve their communities and the need to remain connected to the broader cataloging ecosystem. The choices they make are not always consistent, and the documentation of local practice is often incomplete. But the underlying motivation—a conviction that subject access should reflect the communities a library actually serves—is both principled and persistent.

Implications for the Field

The proliferation of local vocabulary projects poses a genuine challenge to the profession's conception of LCSH as a universal standard. It also represents an opportunity. The headings and frameworks being developed at the margins of the official system encode knowledge about communities and materials that the Library of Congress, operating from Washington, D.C., may be poorly positioned to develop on its own.

Some cataloging professionals have begun to argue for more formal mechanisms to incorporate locally developed headings into the national authority file—not simply to absorb local innovations, but to build a more genuinely collaborative model of subject authority control. Whether that vision is achievable within existing institutional structures remains an open question.

What is clear is that the era of uncontested LCSH universality is over. The institutions building local vocabularies are not, for the most part, trying to destroy the shared cataloging infrastructure. They are trying to make it work for everyone who uses it. Whether the field finds a way to accommodate that aspiration within a coherent national system, or whether the result is a gradual fragmentation of the catalog's common language, may be among the defining questions of American librarianship in the decade ahead.