Since the United States is so large and many values and beliefs can vary from one location to the next. This makes it so that it can be a lot more difficult for people to receive a fair sentence that is the same from one location to another. Initially, someone living in one state might get a much larger sentence than someone living somewhere else even after committing a similar crime.
Since this wasn’t very fair, the government decided to set up some guidelines to make sure that judges everywhere has something to structure sentences off of. These sentencing guidelines are used by judges to determine a range of consequences that different actions can have. The judge may choose to vary the sentence based on the severity of the crime.