A native of Milroy, Pennsylvania, born on June 1, 1829, he and his family moved to Ohio in 1838, where they farmed.
After Rush Clark vacated the speakership for health reasons, Rothrock was elected speaker pro-term.
Upon completing his only term as a state representative, Samuel J. Kirkwood offered Rothrock the rank of colonel in the 35th Iowa Infantry Regiment.
Rothrock caught typhoid fever during the engagement, and after recovering, returned to the practice of law in Iowa alongside W. P. Wolf.
Rothrock was appointed to the eighth district court judgeship in 1866 and succeeded by John Shane upon his elevation as a justice of the Iowa Supreme Court from February 24, 1876, to December 31, 1896, appointed from Cedar County, Iowa.