Why is the state boundary between the United States and Canada straight?

Because the United States draws the boundaries between state administrative regions and Canada in parallel with latitude and longitude.

1. In those years, American surveyors first determined a north-south baseline, which is now the boundary between Ohio and Indiana, and then determined an east-west baseline, drawing an east-west line and a north-south line at regular intervals from the intersection of the two lines, thus forming an independent administrative region, which is the predecessor of today's American state boundary.

2. America is an immigrant country. After the founding of the People's Republic of China, it acquired a lot of land in a short time. At that time, these lands were vast, sparsely populated, without historical division and flat terrain. In order to facilitate measurement and management, the federal land law has gradually straightened most state boundaries. This state in Australia, the border between the United States and Canada, and the borders of West African countries all have similar performances.

The border between the United States and Canada is 8900 kilometers long (including the border between Canada and Alaska, USA). The border agreement between the United States and Canada was signed in 1846. At that time, the two governments decided that the border between the two countries should form a straight line. According to the division of 49 N, there are no military facilities along the line. Citizens of the two countries are free to cross the border and stay in the other country for three months without any diplomatic visa.

Extended data:

China's provincial boundaries are winding.

Compared with the United States, China has a longer history, and it also has its own unique traditions and considerations when drawing boundaries. Generally speaking, all previous dynasties in China distinguished geographical boundaries according to mountains and rivers. From the Tang Dynasty, the imperial court clearly proposed to divide administrative regions according to "mountains and rivers". For example, Henan and Hebei are bounded by the Yellow River, Hunan and Hubei by Dongting Lake, and Shandong and Shanxi by Taihang Mountain. These are typical "mountains and rivers".

For example, Henan should be south of the Yellow River, but a considerable part of northern Henan is north of the Yellow River. Delineate the border according to the "convenience of mountains and rivers" to facilitate the local people and reduce administrative costs.

References:

Baidu Encyclopedia-Treaty between the United States and Canada on the Boundary Delimitation between the United States and Canada

References:

Baidu encyclopedia-American territory