Parallel 36°30′ north — geographic line and historical boundary

Geographic course

The parallel encircles the globe and crosses a range of ocean basins and continental regions. Moving eastward from the Atlantic it passes through parts of North Africa, the Mediterranean vicinity, stretches of western and central Asia, and across North America. Along these longitudes the climate, vegetation and human geography vary: coastal zones tend to be milder, while interior continental areas show greater seasonal extremes. On maps, the line is used as a reference for latitude and for comparative geography.

Role in United States history

The most widely recognized historical role of the 36°30′ parallel is its adoption in the Missouri Compromise of 1820, a federal statute that sought to regulate the spread of slavery in territory acquired from the Louisiana Purchase. Under that compromise, slavery was prohibited in the remaining territory north of the line, with the notable exception of the state of Missouri. The line therefore became a practical and symbolic boundary in sectional politics of the early nineteenth century in the United States. Later political acts and judicial decisions in the mid‑19th century changed the legal framework governing slavery in the territories, but the 36°30′ mark remains a reference point in the history of U.S. expansion and sectional conflict.

Cartographic and legal use

As a geometric feature the parallel has no intrinsic legal power; it acquires practical effect only when adopted in statutes, treaties or surveys. In North America it was cited in legislation and territorial descriptions that related to lands west of the Mississippi River. Surveyors and mapmakers have used parallels such as 36°30′ to lay out boundaries, to describe property limits, and to support navigation and geographic description.

Contemporary significance

Today the 36°30′ parallel is primarily of interest to geographers, historians and educators. It illustrates how abstract geographic lines can be transformed into political limits and how latitude figures in climate, daylength and regional identity. It also serves in comparative studies that consider how political geography interacts with physical geography across different longitudes and continents.

Further context

• As a parallel, 36°30′ is one element of the global grid of parallels and meridians used in mapping and navigation.
• Its historical role is most often discussed in works on the Missouri Compromise and the territorial politics of the early United States.
• For basic definitions and mapping conventions see introductory geographic references and atlases that treat parallels, meridians and coordinate systems.

For readers seeking more detailed primary documents and legislative texts related to the line, consult authoritative historical collections and legal records that cover the Missouri Compromise and subsequent territorial legislation. These sources place the 36°30′ parallel in the wider context of 19th‑century American political and geographic development.

Related topics include the nature of latitude and longitude as coordinate systems, the history of the Louisiana Purchase, and regional studies that examine how a single parallel crosses varied environments and jurisdictions.

See also general treatments of parallels and the specific historical debates surrounding the use of the 36°30′ boundary in U.S. territorial policy.

Reference links: circle of latitude, 36.5° N, equator, United States, Missouri Compromise, Mississippi River, Missouri.