Some national borders follow lines of longitude. For example, the 38th Parallel is the DMZ which demarcates the Republic of Korea (South) from the DPRK (North).
lakes
because they follow rivers
land surveyors as directed by political agreements
Four states in the United States have straight line borders: Colorado, Wyoming, Utah, and New Mexico. These straight line borders were established through surveying techniques rather than natural geographical features.
Which two states have four straight lines as borders
Straight borders are often a result of surveying methods used during land divisions, while crooked borders can be influenced by natural geographic features or historical boundaries established through treaties or agreements. Additionally, straight borders may also reflect efforts to simplify administration and governance in regions with more uniform characteristics.
Some borders are made by natural features, such as rivers. Other times, there might be a straight line determined by geographical latitude or longitude.
if you mean which countries have borders that are entirely made up of straight lines like say the state of Utah then none but if you mean which countries have borders that include at least some lines that are entirely or perfectly straight then probably all or nearly all A few examples like Papua New Guinea and Egypt do however come close to entirely straight borders Land borders are defined by border markers. These are placed by mutual agreement by the two countries and mark out the border. They can be anything from a few tens of metres apart to a few Km apart. Normally they are within sight of each other. The border is deemed to run in a straight line from on border marker to another. Most borders are therefore a large number of relatively short straight lines, and most borders are defined by straight lines. This does not apply to borders which run along rivers or lakes. in this case the border is normally the centre of the river, which is not a straight line. Note a line of latitude (xx °N or yy °S) is not a straight line.
because they want to
Hawaii and New Jersey
Rivers
Colorado