The son of a retired military officer, Cranmer graduated from Brentwood High School in 1974 and received a bachelor of science degree in secondary education and history from Duquesne University in 1978.

After service as a United States Army officer where one of his assignments was as a company commander with the 101st Airborne Division,[3] he returned home and was elected to Brentwood Council in 1991.

But after his election Cranmer found his campaign promise was easier said than done when grocery chains he contacted disparaged the condition of the current shopping center and the topography of the land where it sat.

When a subscriber television was turned on it would automatically "default" to one of the adult channels, each being lightly scrambled but still providing full uncensored audio.

These "mechanical" features made contact with the channels unavoidable, making children vulnerable to programming designed explicitly for adult viewers.

In October of that year Cranmer again gained the national spotlight when Teresa Heinz, the wife of the late Senator John Heinz, a Republican, and later wife of presidential candidate John Kerry, publicly endorsed Democratic incumbent Senator Harris Wofford, who had been appointed to the seat by Governor Bob Casey following her husband's death.

[11][12][13] In 1995 during his campaign for county commissioner, two Brentwood Police officers were involved in an incident during which a young black man named Jonny Gammage of Syracuse, New York, was killed during a routine traffic stop.

[19] He was heralded as a "traitor" to Republicans by commissioner Dunn, who subsequently (unlike Cranmer), switched parties and became a registered Democrat to run for county controller in 2003.

[20][21][22] In summary, the Post-Gazette stated "that despite the political suicide he brought upon himself, this was the turning point that helped the county recover from earlier mistakes".

[34][35] During their administration Mike Dawida and Bob Cranmer also oversaw the rehabilitation and restoration of the famed Henry Hobson Richardson Allegheny County Jail designed in the late 1800s.

The vacant and deteriorating structure was converted to house the new combined home of the juvenile and adult family sections of Allegheny County Common Pleas Court.

The $46 million spent on the renovation project was nearly 23 times the original cost of both of the Richardsonian Romanesque masterpieces, the jail and county courthouse.

[36][37] Cranmer and Mike Dawida worked cooperatively to achieve their city-county goals, and as the Pittsburgh Post-Gazette put it: "The partnership held strong through decisions that got county government back on track."

[39][40] The Post-Gazette commented in 1998 that Allegheny County Commissioners Bob Cranmer and Mike Dawida understand the importance of a strong urban core and, through their partnership, have helped the mayor find ways to do what lesser leadership would considerable unthinkable.

The Post-Gazette would later sum up his time in office with the following when he announced that he would not seek reelection: "By thinning the field and working toward the day when Republicans have a single alternative to the policies of ill-conceived tax cuts, reactionary thinking and government-as-usual, Commissioner Cranmer has made the ultimate political sacrifice.

Papers and associated historical records concerning Cranmer's term in office are filed at the Heinz History Center, (archival storage) in Pittsburgh.

[48] Originally, a ten-county half percent sales tax increase was proposed by the Allegheny Conference on Community Development to fund three projects: Heinz Field, PNC Park, and a major expansion of the David L. Lawrence Convention Center, along with other regional public works infrastructure improvements in all ten counties.

After the rejection of this proposal in a referendum, Cranmer, Mike Dawida and Pittsburgh Mayor Tom Murphy developed Plan B which involved no "new" taxation.

This was due to his discovery that a portion of the Regional Asset District Tax was specifically designated for the "construction and maintenance" of sports facilities.

[61] Due to his support for Plan B his popularity with Republican voters dropped significantly and he announced in early 1999 that he would not run for the newly created position of county executive.

His son was examined by paramedics and taken to Jefferson Memorial Hospital, and Cranmer was charged with simple assault, arraigned in Night Court by Senior District Justice Leonard Boehm and released on his own recognizance the following morning from the Allegheny County Jail.

[71] After leaving office Cranmer set out to record in pictures what he called "the amazingly unique scenery and architecture of Allegheny County."

[72][73] After leaving political office Cranmer wrote numerous op-ed articles and one historical research piece about George Washington in Western Pennsylvania.