WASHINGTON (AP) — With five days left for people to return their census forms, Census Bureau director Robert Groves on Monday urged those in big cities and border regions to step up the response to avoid visits by census takers next month.

So far, about 65 percent, or more than 77 million households, have completed and mailed back the 10-question forms. The Midwest leads the pack, while the southern and western U.S. and big cities such as New York, Chicago and Philadelphia are lagging.

At a news conference, Groves said most of the lagging areas are either rural or have dense populations, or have more minority and non-English speaking people. That was also the case in 2000.

While there have been anecdotal reports of conservatives boycotting or only partially filling out the form, Groves said there is no evidence of that.

“Things are going quite well,” he said, referring to overall mail response, which remains on track to match or surpass the 2000 mail-back rate of 72 percent.

“But the clock is ticking. We would love to avoid sending census takers to large numbers of households around the country,” Groves said.

The Census Bureau is asking people to mail their forms by Friday as it prepares to send more than 600,000 census takers to homes beginning May 1. Homes that have not yet received census forms can call 1-866-872-6868 between 8 a.m. and 9 p.m. to submit information by phone or find out where to pick up a form at more than 40,000 help centers around the country.

The Census Bureau has estimated it would save $1.5 billion in follow-up visits if everyone who received a census form mailed it back. The population count, conducted every 10 years, is used to distribute U.S. House seats and more than $400 billion in federal aid.

The highest participation rates are in Wisconsin, Minnesota, Iowa, Michigan and Nebraska, where return rates range between 71-76 percent. North Carolina and South Carolina, which have participation of 67 percent and 66 percent, have topped their mail-back rate from 2000.

Alaska ranks at the bottom in participation, with 54 percent of households returning their forms. It’s followed by New Mexico, Louisiana, West Virginia, New York, Hawaii, Mississippi and Oklahoma, each with rates of less than 60 percent.

Copyright 2010 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.