Residents of three more large apartment complexes in Philadelphia have not received U.S. Census forms, officials said Wednesday.

Residents of the Rittenhouse Plaza at 1901 Walnut St., with about 120 apartments; the Wireworks at 301 Race St., which has about 90 apartments; and the 104-unit Valmont Towers at 7600 Roosevelt Blvd. had not received forms in the mail, regional census officials said.

Earlier this week, residents of the Society Hill Towers, which has 620 apartments, and 1220 North Broad Street, a 300-unit high-rise, reported that they had not received forms.

The forms should have been delivered by mail the week of March 15, officials said. Completed forms should have been returned last week to reduce the need to send a census enumerator to visit homes.

At the Rittenhouse Plaza, officials said, 104 forms were deemed deliverable by mail and about 15 were deemed undeliverable. They said they could not confirm how many had been received.

"We will continue to work to count everyone. The census isn't even halfway through," said Fernando Armstrong, regional director of the U.S. Census.

Counting runs until mid-August, he said.

The Wireworks and the Valmont Towers were mistakenly listed as "group quarters," a designation for dormitories, group homes, and other buildings where residents do not list individual apartments, Armstrong said.

Rather than receive mailings, group quarters require a visit by enumerators who interview residents, he said.

Enumerators will visit each unit of the Valmont Towers and the Wireworks between May 1 to July 10 during the census "nonresponse follow-up operation," in which enumerators visit all homes that have not mailed in completed forms, Armstrong said.

From July 17 to Aug. 18, census workers will go to any addresses where the forms could not be mailed, he said.

For every person not counted in the census, Philadelphia loses about $2,800 in federal grants, said Patricia Enright, executive director of Philly Counts, citing a study by the Brookings Institution.

Despite the problems with the apartment buildings, Armstrong said, the census has achieved a 62 percent response rate in the city, which is 1 percentage point higher than for the entire 2000 census. He said the number was likely to rise a few more points.

People who prefer to complete the census by telephone should call 1-866-872-6868, he said. Such calls will be taken through the end of July.

The three high-rises of Society Hill Towers were listed in the wrong block by a field worker, officials said.

Philly Counts' Enright said, "The bureau has been incredibly responsive to these problems, and I am confident they are going to do all they can to fix them."

Philip M. Lutz, assistant regional census manager said, "What we're finding in Philadelphia and what we're hearing from our counterparts is that these issues are not unique to Philadelphia."

Contact staff writer Vernon Clark at 215-854-5717 or vclark@phillynews.com.