PHILADELPHIA began 325 years ago as a planned city.

While the city has grown far beyond its original boundaries, William Penn's grid still shapes 21st century Center City. But planning has been more exception than rule in Philadelphia. It seems to capture public attention and have greatest impact at times of profound transition.

Planners in the early 20th century transformed a grimy industrial metropolis into a great cultural center, fashioning the Parkway as gateway to Fairmount Park. Renewal planning in the 1950s accelerated the transition from a manufacturing to post-industrial economy, creating a new office district, new shopping areas, university and medical campuses across the city.

History suggests that when our mayors have embraced planning, with public-private partnerships for implementation, the city made quantum leaps forward. But in the last decade, as many American cities built new light rail, invested in smart-technology for transit and highways, converted expressways to landscaped boulevards and created vibrant waterfronts and civic spaces, Philadelphia let planning lapse, focusing on individual projects rather than infrastructure and civic space.

Why downtown matters

Spring Garden to South Street, river to river, is but 2 percent of Philadelphia's geography. But this compact zone holds 7,100 businesses that pay of 47 percent of private-sector wages citywide — $6 billion annually to residents in every neighborhood, another $7 billion to suburban residents. If you add University City, 57 percent of private-sector wages are generated between Front and 40th, Spring Garden to South Street.

Contrary to myth, post-industrial employers offer broad opportunities, from entry-level to technical to high-skill, high-wage jobs. Buses, trolleys, subways and rail make downtown jobs easily accessible, especially those without cars. In return families pay mortgages and rent, buy food and clothing, send their children to college.

And remember, downtown is a primary source of taxes that support municipal services. The feds are way less generous than during the New Deal or Great Society. Now, 73 percent of Philadelphia's operating budget must be generated locally, making self-reliance a necessity. So let's move beyond false choices: The next mayor simply can't deliver quality services without a competitive environment.

What's changed since '88?

Center City's plan was last updated in 1988. Since, we've moved from dirty and dangerous to clean and safe, from 40 percent vacancy on South Broad to a thriving mixed-use arts district, from an outmoded Civic Center to state-of-the-art expanding Convention Center, from 4.5 million square feet of obsolete office and industrial space to 11,000 new downtown housing units, from a two-hour stop between Washington, D.C., and New York to a thriving tourist mecca, from no outdoor cafes to 187. In 1988 the city was a ghost town at night — now traffic jams mean we must manage success.

Some better proposals from 1988 — enlivening plazas around City Hall and a new transit stop in the office district — never happened. And the prediction of 20 million square feet more office space fell sadly short. But when we've planned for growth — for eds and meds and the hospitality industry — we've exceeded expectations. Where we tolerated a dysfunctional tax system and neglected transit, we paid the consequences: 17.6 percent fewer office jobs than in 1990.

What planning can do

It can provide vibrant civic spaces, better connections to the waterfronts and new ways to overcome highway barriers and blank walls left by urban renewal.

It can enhance a transit system that carries 291,000 riders downtown each day. Dedicated funding, greater frequency, real-time info and maps at all stops, a high-speed fare-collection system can encourage the impulse to jump on trolleys and buses, minimizing autos and traffic.

Planning isn't about how to spend money. It's about creating visions that inspire leaders and attract money. It's the only way to leverage remaining federal funds and tap other sources.

"Planning for Growth 2007- 2012" suggests to the next mayor investments that, when joined with competitive tax policies, can prompt sustained economic growth, improved services and expanding opportunity for all. *

Paul R. Levy is president of the Center City District.