A grader is a machine used to give the right slope to a road. Originally mules were used for this work. Read here how that transformation from mule graders to machine graders happened:
Highway construction is and has been labor-intensive, but after we found this photo we couldn't be happier to be living in our modern, mechanized age.
As you might know, grading is the process of smoothing the base layer of a road to remove divots, washboards and other high or low points. For dirt roads, such as this stretch of US 60 , grading is basically all the roadwork and maintenance that is done. Today construction crews have grading machines for this type of work. We can only imagine those machines are a bit more reliable than the mules and produce less ... um ... waste.