Volcanoes tend to be situated in lines (not necessarily straight lines).
Some volcanoes (like along the west coast of the US) follow the edges of tectonic plates. So the volcanoes will follow the general mountain chain. There is a formation called the Ring of Fire. It is a series of volcanoes around the edges of the Pacific plate (Western US, Eastern Asia)
Map from Encyclopedia Britannica:
Some volcanoes result from a hot spot under the crust with the plate moving over that hot spot (Hawaii). This results in volcanoes appearing in a straight or slightly curved line in areas of relatively flat terrain.
Wiki:
Then you have the outliers that result from some flaw in the crust that allows magma to work its way to the surface. There is one such under Yellowstone (some day it might blow and take out a good chunk of the middle of the US).
Yellowstone, National Geographic: