Definition
A legally authorized allowance paid at a fixed rate per mile to compensate certain persons for travel expenses incurred in the performance of public or official duties. The allowance applies most commonly to:
1. Members of legislative bodies, compensated for travel to and from legislative sessions.
2. Witnesses, compensated for attending court proceedings.
3. Officers of the court, including sheriffs and bailiffs, compensated for travel in executing process or carrying out official functions.
The rate is typically fixed by statute, and the mileage is calculated by the distance of the road usually traveled, not by any shorter or longer route the individual may choose for personal convenience.
Common Language
Modern common usage (Wiktionary): The total distance traveled in miles; the number of miles a vehicle travels per unit of fuel; an allowance for travel expenses at a specified rate per mile; also used informally to mean the usefulness or value extracted from something.
Historical common usage (Webster's 1913): An allowance for traveling expenses at a certain rate per mile; the aggregate length or distance in miles. Webster's also notes "constructive mileage," defined as a mileage allowed for journeys supposed to be made but not actually made.
The common meaning of mileage as a fuel-efficiency measure or as a general idiom for usefulness ("getting mileage out of something") has no legal relevance. The legal term is narrower and more formal: it refers specifically to a statutory entitlement to reimbursement for official travel, not merely any distance-based calculation. Researchers encountering "mileage" in historical legal documents should not assume the modern automotive sense.
Common Confusion
Mileage as a legal entitlement is sometimes confused with general travel expense reimbursement or per diem allowances. The distinction matters: mileage is specifically distance-based and calculated per mile, while per diem covers daily expenses more broadly. In historical statutes and court records, both types of allowance may appear together, and conflating them misreads what an officer or witness was entitled to claim. Webster's note on "constructive mileage" — an allowance for travel not actually performed — flags a further subdivision that historical researchers may encounter in legislative pay records.
Why It Matters in Research
Researchers working with historical court records, legislative journals, fee schedules, and officer expense accounts will encounter mileage as a term of art with a fixed legal meaning. Several navigational points deserve attention:
Distance calculation rule: Bouvier's establishes that mileage must be computed by the road usually traveled, regardless of whether the officer or witness took a different route. This is not merely administrative practice; courts adjudicated disputes over mileage claims on exactly this basis. Researchers reading fee dispute cases should recognize this as the operative legal standard.
Statutory dependence: The rate and eligibility criteria for mileage are entirely statutory. This means mileage allowances vary significantly across jurisdictions and change over time as legislatures revise fee schedules. A mileage rate appearing in an 1870 Ohio statute is not transferable to California records of the same period.
Officers vs. witnesses: The class of persons entitled to mileage is defined by statute and has historically included different groups depending on the jurisdiction. Early American statutes often covered sheriffs, constables, bailiffs, and legislative members explicitly, while witness mileage was sometimes separately governed. Research into witness fee disputes requires attention to whether mileage was included in the applicable fee bill or addressed separately.
Legislative mileage: For constitutional and legislative history research, member mileage was a politically significant allowance. Debates over mileage rates appear in legislative records as substantive fiscal and political controversies, particularly where members traveled long distances from rural districts.
Modern federal context: In contemporary administrative and employment law, mileage reimbursement rates set by the IRS and federal travel regulations bear a family resemblance to the historical legal concept but operate in a different legal framework. Researchers should not assume continuity of doctrine between historical officer mileage and modern employee reimbursement regimes.
Historical Dictionary Support
The historical dictionaries are in close agreement on the core definition. Black's (both editions), Rapalje & Lawrence, and Bouvier's all define mileage as a compensation allowed at a fixed rate per mile for travel in official capacities. Bouvier's is the most informative, adding the road-usually-traveled rule and identifying the class of recipients as officers engaged in public business. Black's 2nd Edition grounds the definition in case law, citing Richardson v. State and Howes v. Abbott as illustrative authority.
None of the historical dictionaries address the modern legislative or administrative dimensions of mileage — IRS standard mileage rates, federal travel regulations, or the labor and employment law context in which mileage disputes now most commonly arise. Researchers working in those areas should treat the historical definitions as foundational background only and consult current statutory and regulatory materials.
Webster's 1913 adds the useful category of "constructive mileage" — allowance for travel not actually performed — which does not appear in the legal dictionaries. This concept surfaces in legislative pay records and is worth flagging when reviewing compensation disputes involving members of Congress or state legislatures.
Jurisdictional Note
Mileage allowances are creatures of statute, and rates, eligible recipients, and calculation methods vary by jurisdiction and era. Historical researchers should locate the applicable fee bill or travel allowance statute for the specific jurisdiction and time period at issue. Federal officer mileage was governed by separate congressional appropriations and fee statutes distinct from state-law regimes.