Here are two numbers: 898,918 and 777,155. The difference between them is the grim distance Philadelphia’s economy has traveled in the final quarter of a century that began with the city proudly calling itself the "workshop of the world."

The first figure represents the number of jobs in the city in 1975. The second is the jobs figure two decades later, in 1995. Where did the missing jobs go? To the suburbs, to the Sun Belt, to places all over the globe. Why did they go? The reasons range from global trends to local errors. What’s clear, in retrospect, is that sometime after the Second World War the city of Philadelphia got trapped in a punishing cycle.

Some of the city’s jobs moved out the path of the new interstates to the suburbs; others moved to the eager labor markets of the developing world. Some jobs disappeared because companies increased productivity; others left because city problems and city taxes made it hard for businesses to increase productivity.

As the job base declined, so did the relative income of the residents who remained. The loss of jobs and income led to social problems, which produced increased demand for government services. Those services had to be paid out of revenues extracted from a reduced tax base, meaning higher tax rates for businesses and working people. The social costs and high taxes produced by lost jobs led to the loss of more jobs and working residents.

A dramatic shift in available jobs from manufacturing to the service sector complicated the cycle. In 1950, the city had more manufacturing jobs than service jobs. By 1990, service jobs outnumbered manufacturing by about five to one. This hurt in two ways. The rapid change left many city residents with job skills out of synch with the job market. And, though service jobs tend to get a bum rap, one low-level job in the service sector was less likely than a factory job to support a family by itself.

If the first term of the Rendell Administration was above all about righting the city’s fiscal house, the second term was mostly about increasing the job base. As a token of success, the city added 10,000 new private-sector jobs in 1997-1998, the first sustained period of job growth since the recession rebound year of 1984. As a token of the challenge, that 1 percent job growth lagged far behind national rates in a boom economy.

While Mayor Rendell brought great energy to the hunt for jobs, his efforts did not begin with or wait for a full public dialogue about an overarching jobs strategy for the city. At forums this year, citizens sifted through the ambiguous examples and evidence of the Rendell years and sorted out three distinct jobs strategies to attack what they named as the central problem: