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GlossaryFire and EMS reporting

Fire Department Identification Number

An FDID identifies a department within a state in historical NFIRS records. Learn why state context, leading zeros, and separate NERIS IDs matter.

A Fire Department Identification Number, abbreviated FDID, identifies a fire department within a state's reporting system. In historical National Fire Incident Reporting System records, it is a state-assigned five-character identifier. Interpret it together with the state and reporting system; the FDID alone is not a universal nationwide department identifier.

What the identifier connects

An identifier lets records be associated with a department even when its name is shortened or written differently. In NFIRS, the FDID belongs in the department-identification portion of an incident record, separate from the incident number.

USFA's 2015 NFIRS reference guide defines the FDID within a state and permits numeric or alphanumeric characters. It calls for leading zeros when needed to fill the five-character field. That formatting matters when importing an old file into software that might otherwise treat the field as an ordinary number. NFIRS reference guide, Basic Module section A.

Example

Hypothetical example: A historical file contains state A with FDID “00123” and state B with FDID “00123.” Those entries are not evidence of the same department. The state distinguishes their reporting contexts.

If a spreadsheet converts “00123” into 123, the display loses the expected leading zeros. An analyst should preserve the identifier as text and use the documented state-and-department combination when joining records, rather than matching every occurrence of 123 nationwide.

Common confusion

An FDID is not a station number, apparatus identifier, or incident number. A department can operate multiple stations and respond to many incidents while retaining the same department identifier.

It is also different from a NERIS Entity ID. USFA describes NERIS identifiers as nationally unique and distinguishes them from state-level FDIDs. A historical FDID should not be relabeled as a NERIS identifier or mechanically converted without a verified mapping. USFA NERIS identifier explanation.

Read the identifier's history

Check the source's state field, identifier format, reference year, and organizational changes. Department names, mergers, service areas, and reporting arrangements can change. Matching an identifier is not by itself proof that organizational coverage remained identical over time.

For current reporting, consult the applicable system rather than assuming a legacy NFIRS field remains the governing identifier. Keep any verified crosswalk with its source and date, and distinguish an agency identifier from a separate record identifier when removing duplicates.

Sources