Ms. Burden argues that gentrification is merely a pejorative term for necessary growth. “Improvement of neighborhoods — some people call it gentrification — provides more jobs, provides housing, much of it affordable, and private investment, which is tax revenue for the city,” she said. On her watch, the administration has undertaken financing 165,000 units of affordable housing by 2014, of which more than 130,000 have been built, and has created projects like Via Verde, the handsome, eco-friendly subsidized development in the South Bronx. “We are making so many more areas of the city livable,” she said. “Now, young people are moving to neighborhoods like Crown Heights that 10 years ago wouldn’t have been part of the lexicon.”

FOR developers, the clock is ticking. Though the Bloomberg administration won’t leave office for 19 months, most projects that require rezoning or other Planning Department approval can take at least 18 months to get through the process. And the administration’s overall friendliness to development means that most builders with projects on the drawing board are scurrying to get them passed before the term’s end, rather than face the uncertainty of the next administration. (Ms. Burden could stay on as the head of the Planning Department if the next mayor wanted her to, though she has given no indication that she plans to stay.)

Adding to developers’ urgency is a market that appears to be on an upswing after years of sluggishness, and the desire to avoid getting mired in the coming city election year, when there is greater likelihood that projects could become politicized.

First, the projects must be certified, which involves conducting extensive environmental studies, including analyzing traffic patterns and air quality. Some projects take years and several iterations before they are certified. Projects then enter a seven-month public review, in which City Planning, the local community board, the borough president and usually the City Council hold public hearings and provide comments. During the public review, projects are often further modified, but it is rare that a certified project doesn’t pass the public review.

One project that is on the fast track is the rezoning of Midtown East, which broadly runs between 40th and 57th Streets east of Fifth Avenue. Ms. Burden and her team are preparing a study they hope to release in June that could ease height restrictions in the area.

The buildings in Midtown East, especially those along Park Avenue, have an average age of 68 years, far older than London, at 60 years, and business centers like Shanghai, at 10 years. The area’s current zoning has severe height limitations, and in fact, many of today’s skyscrapers were grandfathered in when a new zoning resolution was passed in 1961. This means that if today’s building owners were to tear them down and build anew, they would have to build smaller.