He attended the United States Military Academy at West Point in 1964,[1] followed by the University of Illinois at Urbana-Champaign.

Johnson majored in history and graduated in 1969 Phi Beta Kappa, receiving the Bronze tablet,[2] an honor given to the top 3% of undergraduates.

After the 1990 census, Johnson was drawn into the same district as Democrat Helen F. Satterthwaite, who had long represented the other side of Urbana, as well as the University of Illinois at Urbana-Champaign.

Johnson "underestimated the value of seniority," spokesman Phil Bloomer says of his boss' decision to run for a fifth term.

At the end of June 2006, Johnson had over $130,000 available for spending for his 2006 campaign, more than double the total amount raised by his opponent at that point.

On March 14, 2012, Johnson endorsed Texas Congressman Ron Paul in the 2012 Republican Presidential primary in Illinois.

[16] On April 5, 2012, just days after winning the Republican nomination for the reconfigured 13th, Johnson announced his retirement from office, to the surprise of many.

[15][18] In the House, Johnson's voting record was the most moderate among Illinois Republicans outside of the Chicago metropolitan area.

In 2010, American Conservative Union gave him its second-lowest rating among Illinois Republicans,[citation needed] behind only Mark Steven Kirk of the 10th District.