At precisely noon, Julio Cesar Acuna stood at the foot of the Angel of Independence, a statue where Mexicans gather in times of national celebration, and sang the national anthem as loud as he could.

Throughout Mexico and around the world, many Mexicans joined him, pausing Wednesday to celebrate the 150th anniversary of the national anthem. Even in cinemas, where movies were halted, people sang as part of a government-backed campaign to promote national identity, and maybe even provide a distraction from the country's nagging crime and poverty.

"It's a way of uniting the country," said Acuna, 29, a hotel executive waving a large Mexican flag as cars and buses slowed and honked their horns in solidarity.

"This is a moment to forget about crime and the growing disparity between rich and poor," said Christian Victoria, 24, manager of a courier company who also came out to the statue to place his hand over his heart and sing with his countrymen.

The anthem was written in 1854, a few years after Mexico lost nearly half its territory in a war with the United States. Reflecting the mood of those times, the anthem is filled with lines such as, "War, war without truce against those who would attempt to blemish the honor of the fatherland! War! War! The patriotic banners drenched in waves of blood."

Many commentators this week have raised the possibility of softening the lyrics to suit more modern times, especially since schoolchildren sing the song every Monday morning. But others have defended it as an important part of Mexican heritage.

Jose Raul Gutierrez Serrano, one of the private promoters of the anthem-singing project, said the song can have modern interpretations: "War is not just about blood, you can have war against injustice."

Officials at the Mexican Embassy in Washington and at consulates in Los Angeles and Chicago said hundreds of Mexicans stopped what they were doing and joined the chorus. "It was emotional," Mireya Magana, an official at the Mexican Consulate in Los Angeles, said in a telephone interview. She said many people who had come to get passports or other documents stood at attention while in line and sang.

"I felt the patriotism and the flag, it was very beautiful," said Enedino Aguirre Cano, a Mexican immigrant who sang with 100 others in the Parque de Mexico in Los Angeles. "We are grateful to this country for the opportunity to live here," he said in a telephone interview. "But it's nice to feel the nostalgia from home, and it was nice to hear our anthem."

The burst of patriotism came hours before the annual Grito de Independencia -- shout of independence -- which is held each year on the night before Sept. 16, Mexico's independence day. President Vicente Fox stood at the central balcony of Mexico City's central square on Wednesday night and led the nation in the rousing cry, "Viva Mexico!"

Fox, his wife, Martha Sahagun, and Interior Minister Santiago Creel led the noontime singing in Chapultepec Castle at the opening of a new exposition about the anthem. At the castle on Sept. 13, 1847, six young military cadets, some of them wrapped in the Mexican flag, are said to have chosen to fight to their deaths against invading American troops.

"When we sing the hymn we're not only saying to the world that we are Mexicans, but we are saying to each other that we are compatriots, that we are part of a culture, of a history, and that we have the same identity," said Creel, a likely candidate for president in 2006 who was a key force behind the public singing.

Small crowds stopped to sing in barbershops, restaurants and offices of the state-owned oil company, Pemex. The grocery chain Grupo Gigante said it was going to play the anthem in all 230 of its stores.

Shortly before the designated hour at the Tasquena bus station, the largest bus and train depot in the southern part of the city, Pilar Abarca Perez said she planned to sing the anthem because, "We are losing our values and we need to rescue them." But while she and others liked the idea, others said they thought it was a little silly or contrived.

At 12, no one stopped to sing. The anthem blared loudly from a radio in a small shop; people eating tacos next door never even looked up from their lunch. The young man running the shop finally snapped off the radio, looking annoyed, as he loaded soft drinks into a large bucket of ice.

"I'm too busy working to sing," he said.

Mexican Interior Ministry workers pause to sing the national anthem during a celebration to mark the song's 150th anniversary, a day before the country marks its independence.