A local union, often shortened to local, known as a union branch in the United Kingdom, is a locally-based trade union organisation which forms part of a larger, usually national, union. These bodies are designed to represent the union's members from a particular area, company or business sector. Locals have their own governing bodies which represent the interests of the larger union while at the same time responding to the desires of their constituents, and organise regular meetings for members. They may also affiliate to a local trades council.

In the United States and Canada, locals are usually numbered. In the printing industry, they were traditionally known as "chapels", led by the "Father" or "Mother of the Chapel".