The original purpose of this paper was to discover why Cache County, Utah at one time taxed towns now located in the State of Idaho. Later, it became apparent that a history of the forty - second parallel was necessary to fully understand the reasoning used by both the Federal and local governments in setting up the political boundaries of Utah and Cache County. Therefore, it was necessary to research the records of the Federal Government, Cache County Government, the LDS Journal History, and diaries of residents of Cache and Bear Lake Valleys, as well as detailed accounts of Spanish and Mexican negotiations with the United States. I also felt it necessary to obtain copies of maps drawn in the 1800s to appreciate the geographical knowledge available at the time. Boundary decisions in the western United States appeared to be the result of compromise more often than not. The forty - second parallel boundary was originally made to appease two independent nations. Because this spirit of compromise continued in the formation of territories after the United States gained control over both sides of the line and precedent was followed more readily than logic, the boundary did not fully satisfy residents on either side of the border for many years .