 In 1878 , Rollin J. Reeves surveyed and marked the border between the newly created State of Colorado and the Utah Territory . Reeves located the sandstone shaft marker placed by Robbins at today 's Four Corners Monument . He then began to survey and mark the border between Colorado and Utah from this point northward . In 1901 , Howard B. Carpenter surveyed and marked the border between Arizona and Utah , completing the survey of borders making up the Four Corners Monument . 
