Organizers of Hands Across America said yesterday they will need about 250,000 people to fill the District and Maryland portions of a planned May 25 coast-to-coast human chain that is expected to raise millions of dollars for the nation's hungry and homeless.

Nearly a third of the places along the 4,100-mile, Los Angeles to New York route have been purchased by individuals and corporate sponsors, according to the project's promoters, and sign-up efforts here got a considerable boost yesterday from singer Kenny Rogers.

"What we need is for that line to hook up," said Rogers, one of four celebrities running the event, who spoke at a Hands Across America rally in Farragut Square. "This is a once-in-a-lifetime situation . . . . This is a moment in history."

Rogers, linking arms with local supporters, led a crowd of several hundred in singing along to a recording of "Hands Across America," a song that is supposed to do for this project what "We Are the World" did for famine relief in Africa. Hands Across America is a spinoff of the USA for Africa group.

Organizers estimate they will need 5.4 million people -- roughly 1,320 participants per mile -- to form a complete chain across the country. In addition, 45,000 volunteers are being recruited to serve as monitors along the route.

It costs $10, $25 or $35 to join the line, and specific spots may be purchased in this region at TicketCenter outlets or by calling (800) USA-9000. Ticket holders will later receive a souvenir of their participation, depending on the amount of their donation.

The full Maryland and District route will extend southwest from Newark and Elkton, Md., travel through Baltimore and the District and turn northwestward into Maryland again, continuing through Rockville, Frederick and Hagerstown to the Pennsylvania border.

About a third of the places in line, including half of the District route, have been filled, according to Donna Brazile, the project's D.C. coordinator. She said numerous local business firms, church groups and community organizations are buying specific blocks or as much as a mile or more along the Maryland and District route.

"Upper Wisconsin Avenue is taken, and the Mall area and downtown are gone," Brazile said.

But organizers say they still need people for the portion of the route that runs through Wards 5, 7 and 8 of the District. About 40 percent of the District route travels through Ward 5, which constitutes most of the city's Northeast sector.

D.C. Council member William Spaulding, who represents Ward 5, participated in yesterday's rally, and the D.C. Board of Education is expected to buy a section of the line in front of its downtown headquarters. Brazile said she is still waiting for Mayor Marion Barry and the council as a whole to sign up for spots along the route.

The Catholic Archdiocese of Washington and the Jewish Community Council of Greater Washington have each pledged to buy a mile worth of spots in the District and another mile in Maryland. In addition, the city's gay community agreed to buy several blocks after the route was shifted to include portions of P Street NW