Geometric Boundary – Definition & Examples (Human Geography)

geometric boundary examples

A geometric boundary is a political boundary that takes on a clear and neat geometric shape.

The benefit of geometric boundaries is that they are easy to mark on a map and easy to understand. However, they’re often criticized for failing to acknowledge the pre-existing ethnic and cultural divides between people who live on either side of the boundary lines.

These boundaries are often politically negotiated rather than created through consideration of the geographic features of the land or settlements that might already exist along the boundaries.

Definition of a Geometric Boundary

Put simply, a geometric boundary is a political or territorial boundary that has a consistent and clear geometric shape such as a square, line, or circle on a map.

Examples of Geometric Boundaries

1. The 49th Parallel

In 1818, the United States and the United Kingdom (then including the Dominion of Canada) reached an agreement known as the Convention of 1818. As part of the agreement, both countries agreed to establish the 49th parallel as the boundary between their respective territories.

The agreement also allowed for joint occupation of the Oregon Country, which was located south of the 49th parallel.

The Convention of 1818 was largely motivated by a desire to avoid conflict between the two countries. At the time, both the United States and the United Kingdom were vying for control of the Oregon Country. However, by agreeing to establish the 49th parallel as the boundary between their territories, both countries were able to peacefully co-exist in the region.

The Convention of 1818 ignored the fact that Native American tribes lived along both sides of the border. As a result, the boundary was superimposed over native tribal lands.

2. Saskatchewan

Saskatchewan’s borders are all straight lines. This is, in part, because the province is located in the prairies where there are few natural features to set clear borders.

Furthermore, when Saskatchewan became a Canadian province in 1905, its borders were drawn based on surveyors’ reports rather than conflict. these reports indicated that the most suitable location for the provincial capital was near the geographic centre of the province.

As a result, the provincial government decided to create rectangular divisions.

While the border appears perfectly straight on a map, the curvature of the earth means that small adjustments need to be made along the Manitoba-Saskatchewan border so it remains square and doesn’t thin itself out on the northern edge.

3. The Indonesia-Papua New Guinea Border

If you look at Papua New Guinea, you’ll notice that its eastern border with Indonesia is a straight line. This because half of the island was invaded by Indonesia in 1962.

At this time, the Indonesian government began a military operation called Operasi Trikora in an effort to annex the western half of New Guinea, which was then known as Papua.

The Indonesian military started by bombing towns and villages in the area and then sending in ground troops. The Papuan people resisted the invasion, but they were outnumbered and outgunned by the Indonesian soldiers. Over the next few years, hundreds of Papuans were killed or imprisoned, and many more were forced to flee into the jungle.

In 1969, a UN-sponsored referendum was held in which the people of Papua voted overwhelmingly to become part of Indonesia.

4. The Australian States and Territories

Australia’s states and territories were carved up over the course of several centuries, as the country was explored and settled by Europeans.

As with many colonized nations, the borders were drawn before many people had settled there, so borders were drawn by surveyors rather than via ethnic divisions.

As a result, most of the borders feature straight lines.

The first state to be established was New South Wales, in 1788. This was followed by Tasmania in 1825, Western Australia in 1829, South Australia in 1836, Victoria in 1851, and Queensland in 1859.

The final state to be carved out of the Australian continent was Northern Territory, which has three square edges.

In 1901, the six colonies came together to form the Commonwealth of Australia and there are virtually no border disputes due to the nation’s cohesive federated identity.

5. Central and Western United States

As with Australia and Canada, the US states were drawn up by surveyors before significant colonization had taken place. This has led to a more geometric shape to the state borders.

One clear exception is the Rio Grande river that marks the eastern side of the border between the USA and Mexico. This border was fought over in the US-Mexico war in the 1840s, and thus, was the result of a political compromise. As with many political compromises, the border followed a geographical feature that would have been a natural chokepoint for an invading army from the North or South.

6. The Canada-Alaska Border

The Canada-Alaska border was set by the Anglo-Russion Convention of 1825 when Alaska was still in Russian hands.

The convention agreed that the border between Canada and Alaska would follow the 141st meridian west, cutting north through the continent. On the southern side, the border does not follow a straight line, but (at the time) weaved itself at a distance of ten marine leagues from the coast until just north of Prince Rupert.

The effect is that a straight line is drawn through the continent with Alaska on one side and the Canadian Yukon territory on the other. This line stretches for 1,244 km (786 mi).

7. The Gadsden Purchase

The Gadsden Purchase was a treaty between the United States and Mexico that was finalized in 1854. The treaty resulted in the purchase of approximately 30,000 square miles of land in what is now southern Arizona and New Mexico for $10 million.

This purchase is demonstrated by straight lines as a map that were negotiated not through wartime pressure and USA hegemonic coercion, but through good faith negotiation. This allowed the purchase to be conducted through surveying techniques that led to straight lines in the carve-up of the landscape.

The primary motivation for the purchase was to secure a route for a transcontinental railroad. However, the treaty also allowed for the annexation of the Mesilla Valley, which included the present-day city of Las Cruces, New Mexico.

The Gadsden Purchase increased the size of the United States by nearly one-third and helped to establish the country as a continental power.


Geometric boundaries are generally clear shapes such as straight lines and arcs that don’t follow the natural features of the cultural landscape. For the most part, these boundaries are negotiated before people settle on the land (making them examples of antecedent boundaries). By contrast, the types of boundaries that are settled through war or negotiations between settled ethnic groups, known as consequent boundaries or subsequent boundaries, tend to follow cultural contours or visible geographic lines in the landscape (such as Hardian’s wall, a relic boundary), meaning they don’t tend to look like geometric shapes.

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Dr. Chris Drew is the founder of the Helpful Professor. He holds a PhD in education and has published over 20 articles in scholarly journals. He is the former editor of the Journal of Learning Development in Higher Education. [Image Descriptor: Photo of Chris]

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