JOHNSTON'S PRACTICE spanned fifty-four years, from the establishment of his office in 1882 to his death in 1936. One of the hallmarks of his work was its deep sense of humanism, indicated both by his emphasis on long-term functional and structural viability and by his installation of ornamental programs specifically suited to the building's uses. As one of his contemporaries put it: "Time has demonstrated that the patient insistence with which he forced certain convictions often caused his clients to build better than they knew."

Clarence Johnston designed more buildings and created a broader range of urban environments than any other figure in Minnesota's history.