Hartwig earned All-Conference and second-team All-State honors as a senior offensive tackle at Valley High School in West Des Moines, Iowa.

Hartwig played college football for the University of Kansas where he was a three-year starter at right tackle who appeared in 38 games with 34 starts.

In 2003, he started every game at center for Titans and helped Steve McNair lead the league in passing while Eddie George recorded his seventh 1,000-yard rushing season.

Hartwig signed a free agent contract with the Carolina Panthers in 2006, starting one game before being placed on injured reserve with a groin injury.

On March 18, 2008, the Pittsburgh Steelers signed Hartwig to a two-year contract, worth approximately US$4 million.