McJohnston was a professor of economics at Ohio State University and later at the University of Illinois in 1913. He had also worked as a copywriter, sales correspondent, and editor at two magazines. He authored several books, papers, and articles such as "Impression Analysis Improves Sales Letters" and "Business Corresponsdence", and The Brevity Book on Economics The Alexander Hamilton Institute (a well-known correspondence course provider of its day) considered his works as a part of their main instruction for both accounting and advertising.
Prior to his more noted work in academics and business, McJohnston was a business instructor and the seventh head college football coach for the Carroll College (Wisconsin) Pioneers (now called "Carroll University") located in Waukesha, Wisconsin and he held that position for the 1908 season. His career coaching record at Carroll College was 1 wins, 5 losses, and 0 ties. This ranks him 26th at Carroll College in total wins and 25th at Carroll College in winning percentage.