its the equator
That would be latitude or longitude.
A line of longitude may also be known as a meridian.Meridians (lines of Longitude) are great circles that go round the Earth through the North and South Poles. So they represent one-half of a polar circumference of the planet.The Prime Meridian runs through England (Greenwich) and is 0 degrees longitude.
Border
The lines of longitude are vertical; longitude measures the horizontal distance from 0 degrees longitude. Here is a mnemonic that helps me: Latitude sounds a little like 'ladder-tude', and the rungs of a ladder are horizontal. I picture myself 'stepping up or down' the lines of ladder-tude, and this moves me farther north or farther south. That leaves vertical for longitude. While the lines of longitude are drawn from north to south, their locations measure a parameter that changes from east to west; longitude tells you how far east or west you are (in degrees, not distance) from the prime meridian (zero degrees longitude). Lines of latitude are drawn from east to west, and they measure how far north or south you are. So running the risk of confusing you, the "concept" of longitude (what is your position east/west of the prime meridian) is really horizontal in nature. This can be a little hard to grasp. Draw a line on a piece of paper; make the line exactly one inch from the left margin. You have drawn the line 'up and down', but the line is there to tell you how to get one inch from the margin (left-right) no matter where you are on the paper. And no matter where you are on the line, you are one inch to the right of the left margin. So if you travel up and down a line of longitude, you might cover several thousand miles, but you haven't budged from your measure of longitude-- how far you are (in degrees) from the prime meridian. As you travel along your line of longitude, you see hash-marks with changing numbers of degrees. These are not changes in longitude, but in latitude. They answer: How far north or south am I, along this line of longitude? When doing navigation, the simple thing is that lines of longitude are all long. Since they all go through both the North and South Pole, they are all the same length. Latitude lines vary in length. Latitude: LAT=FLAT Longitude: LONG (heights)
equator
Indiana' eastern border is 84 degrees 49' W.
California has a northern border and an eastern one, but no "northeastern" border. However, the boundary between California and Nevada does appear to follow close to the meridian of 120 degrres west, for about 200 miles.
The closest Idaho ever gets to 100 degrees west longitude is along its eastern border with Wyoming, at about 111 degrees west.
The eastern line of longitude for Michigan is approximately 82.4°W, and the western line of longitude is approximately 90.42°W.
The meridians of 0° and 180° longitude separate the eastern and western hemispheres.
South Dakota and Wyoming share the same line of longitude as the western border of Nebraska.
The eastern line of longitude of Oklahoma is approximately 94.43°W, and the western line is around 100.0°W. Oklahoma spans from approximately 94.43°W to 100.0°W longitude.
The line of longitude that forms part of the border between Namibia and South Africa is approximately 20 degrees East. This line runs north-south and is part of the international boundary separating the two countries. The border is defined by a combination of this longitude and other geographical features.
Zero degrees
Maine
The eastern line of longitude in South Carolina is approximately 78.5428°W, and the western line of longitude is approximately 83.3534°W. These lines help define the borders of the state and indicate its position within the coordinate system.