TriState

Tristate, or tri-state, is a term used in different contexts to denote three distinct states or areas. In technology, it describes a three-state logic concept or a component capable of three output conditions. In geography and regional discussion, it refers to a metropolitan area that spans parts of three states.

In electronics, tristate refers to three-valued logic used in digital circuits. A tri-state buffer or driver can place its output in one of three conditions: logic high, logic low, or a high-impedance state. The high-impedance state effectively disconnects the device from a shared communication bus, preventing electrical conflicts when multiple devices may try to drive the same line. By enabling or disabling the driver, circuits can coordinate access to common data paths, which is essential for microprocessors, memory interfaces, and system-on-chip designs.

Geographically, the term tri-state area describes regions where a metropolitan area crosses state boundaries. The most widely cited example is the New York metropolitan area, which includes parts of New York, New Jersey, and Connecticut. Other examples in the United States include areas around Cincinnati (Ohio–Kentucky–Indiana) and, in some descriptions, parts around Chicago. The exact boundaries of a tri-state region are informal and can vary by source, organization, or local usage.

In summary, tristate commonly appears in electronics to describe three-state logic and high-impedance bus behavior, and in regional terminology to denote metropolitan areas that span three states. See also tri-state logic, high-impedance, and tri-state area.