Philadelphia — When former Congressman William J. Green became this city's 125th mayor Jan. 6, 1980, many thought Philadelphia would once again emerge from the the long shadows of New York and Washington into national prominence.
His predecessor, Frank Rizzo, left the city racially polarized and with a reputation for violence. The new mayor was expected to open a new era of enlightenment.
But Mayor Green has had his hands too full with city fiscal problems, growing opposition from blacks, and rising unemployment (due partly to the axing of 15, 000 government jobs) for him to be much of a knight in shining armor.
Recent charges of corruption in his administration, vigorously denied, didn't help any, either, even though they turned out to be unfounded.
The black community's dissatisfaction with Mayor Green stems from what it sees as a lack of commitment to affirmative action. There has also been growing unhappiness over the city's acute shortage of decent inexpensive housing.
A leading Philadelphia architect told a City Council hearing recently, ''The Philadelphia Housing Authority is a horror story all to itself.''
Mayor Green hasn't announced his intention to seek reelection -- and his chances of winning are seen as not so strong as they were 1979. His victory then was seen as due at least partly to an anti-Rizzo vote rather than a pro-Green one.
There is almost sure to be at least one significant black mayoral candidate in the Democratic primary. Mr. Rizzo is sending out signals that he might seek reelection, too. Although the city's constitution was altered during his second term to keep him from running again, Rizzo would be allowed to run next year.
But despite the incumbent's difficulties, there is a perception of a new ''Green era'' in bloom:
* Philadelphia remains one of the safest major cities in the country, according the Federal Bureau of Investigation's uniform crime statistics. Much of the credit for this is due to Mayor Rizzo's campaign against violent crime, which succeeded in making the streets safer.
* Racial tensions have eased, partly the result of improvement in the police force under Mayor Green.
* Mayor Green has given strong backing to new efforts to boost Philadelphia's tourism and convention potential. In just two years, downtown Philadelphia has become a much pleasanter place to work and live.
* Despite his aloofness from the press, Mr. Green is seen to have restored a certain dignity to the mayor's office. Even his unpopular stands are respected for being carefully thought out.