Rafael Bamba doesn't know when, where or if the U.S. Census Bureau will count him. It's going to be tricky, he admitted, considering he sleeps on whatever sidewalk is handy in downtown San Francisco.

But he does know this: He wants to be counted.

"I don't really know why, but it's important," said Bamba, 55, a former roofer who has been homeless for a decade. "A person just wants to let people know they're there, that they're alive."

About 50 feet from the Glide Memorial United Methodist Church doorstep where he was dozing Tuesday morning, getting ready to line up for lunch, a room full of census officials and volunteers were getting ready to answer Bamba's wish.

The group was heading outside to begin its second full day of counting the homeless, and the concentration this day was on soup kitchens. Glide runs one of the most popular ones in town, feeding more than 1,000 people every day at lunchtime, so it was a prime spot for counting.

"The homeless are some of the most daunting challenges we have at the census, but we are more determined than ever before to do the most complete job we can," said Michael Burns, deputy regional director for the census bureau's Seattle office, which oversees Northern California and much of the West.

The importance of being complete with street people, he said, is the same as it is for counting housed people. The more accurate the count, the more accurately federal resources and community attention can be given to a particular region.

That's because a lot of federal money is allocated according to population, and sometimes in the case of needs-specific programs, according to race and age. According to Burns' staff, $1,700 in federal funding is funneled annually to California per person, based on census counts.

In San Francisco, the figure is $3,862, said Tony Winnicker, spokesman for Mayor Gavin Newsom, who, like Burns' staff, based his number on studies by the Brookings Institute. The figure could have been higher, Winnicker said, but the city's population was undercounted in 2000.

"The census is about power, money and justice," Burns said. "So it's crucial to get it right."

The count of homeless people for the 2010 Census is being conducted all over the nation this week. In San Francisco, more than 800 staffers and volunteers are fanning out to shelters, encampments and doorways they've identified after speaking with city organizations and experts who deal with the homeless.

Dariush Kayhan, Newsom's director of homeless policy, said his staff had advised the census counters on locations and techniques, so he has high hopes they can get a complete count. The city's last homeless tally, taken in January 2009, found 6,514 unhoused people.

The U.S. Census is conducted every 10 years, and the bureau has made concerted efforts to count the homeless since 1980. Homeless people will be asked the same sorts of questions housed people are - including name, age, sex, race and location - and no answers will be released to law enforcement or immigration agents, Burns said.

"The trust factor is very critical, of course," said Glide's pastor, the Rev. Cecil Williams. "The homeless are receptive if they get the proper information, if it looks like it helps them. Also, some of them cannot fill out the papers, so they're also receptive if someone helps them.

"I think everyone understands that it's important."