Millions of demonstrators marched at squares around the country Sunday to celebrate May Day and in support for the 1961 Cuban revolution.

Workers, including thousands of trade union members from the education sector, lead the country’s main parade in Havana, against the backdrop of the 55th anniversary of the country’s illiteracy campaign and declaration that Cuba was free of illiteracy.

“It is a commitment to participate in the parade because this way we celebrate the anniversary of the literacy campaign,” said university professor Sergio Ortiz. “Thanks to that time Cuba currently has the highest rates of education in Latin America.”

Guest from more than 200 organizations representing 68 countries witnessed the festivities as the head of Cuba’s largest union said that the U.S. lifting a more than 50-year economic blockade is an indispensable condition to fully normalizing relations with Washington.

Ulises Guilarte also reaffirmed Cuba’s commitment to improving the efficiency of the current generation of workers to meet the needs of the country, increasing revenues, improving products and services and reducing imports.

One worker, Luis Arias, shared Guilarte’s vision for the future. “The parade on May Day, is a celebration of workers in Cuba. We came with family to support socialism and the achievements of our working class,” he said.

The parade was the first mass rally held after the 7th Congress of the Communist Party of Cuba earlier this month ratified initiatives for the country.

The May Day parade has historically been an expression of the will of Cuba’s citizens to play a leading role in a process for change.

Under the banner: “For Cuba: Unity and Commitment”, the march marked the 90th birthday of the leader of the revolution, Fidel Castro, the 60th anniversary of the landing of the Granma expedition that launched the overthrow of Fulgencio Batista and, 55 years since the failed Bay of Pigs invasion to remove Castro.

Using the hastags #todosmarchamos, #Cuba and #1Mayo, thousands of messages have been posted on Twitter urging Cubans to participate in the parade.

Posters, flags and support for the revolution and socialism were accompanied by thousands of tweets.

Delegations from Sweden, Russia, Chile and Uruguay, among other countries, also used social media to announce their participation in the parade.

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