Convert Acre (US Survey) (ac (US)) to Square Mile (US Survey) (mi² (US)) instantly.
About these units
Acre (US Survey) (ac (US))
The US survey acre is based on the US survey foot, making it slightly different from the international acre. With a value of 43,560 survey-square feet, it appears extensively in historical property records and federal land surveys. Because millions of acres in the United States were mapped using PLSS, the survey acre remains necessary for interpreting legal land rights, even though modern mapping often uses metric units or the international foot. This specialized acre illustrates how subtle unit differences can survive for centuries due to legal and administrative inertia.
Square Mile (US Survey) (mi² (US))
The US survey square mile is extremely close to the international square mile but is defined using the US survey foot, a slightly different value than the international foot historically used in land surveying. This unit appears in American land deeds, cadastral maps, and federal land management documents. The Public Land Survey System (PLSS), which divided much of the western United States into townships and sections, relied heavily on survey-based square miles. Although the modern US has transitioned to the international foot (as of 2023), historical land descriptions remain legally tied to the survey-based definition, ensuring its continued relevance.