Fifty years ago today, Fidel Castro's Cuban revolutionaries seized their nation.

Fifty years ago today, rebel forces captured the city of Santa Clara in central Cuba, sending the island nation’s dictator, Fulgencio Batista, into a New Year’s Eve panic. He fled for exile in the Dominican Republic. A week later, a bearded 32-year-old lawyer named Fidel Castro marched triumphantly into Havana to claim his prize.

El Comandante is still there and still in charge, although earlier this year, he surrendered day-to-day control of the nation to his brother, Raul. Fidel Castro has survived 10 U.S. presidents starting with John F. Kennedy, who severed diplomatic relations with Cuba in 1961, when it entered the Soviet Union’s embrace.

The world has changed drastically in 50 years, but the United States and Cuba remain fierce political adversaries. Their populations, paradoxically, are intertwined, even as the U.S. economic embargo restricts the flow of people, money and products to and from the tropical island of 11 million people.

The embargo is an anachronistic vestige of Cold War politics that no longer serves much purpose. Mr. Castro’s ill health, along with the beginning of President-elect Barack Obama’s administration, offers a special opening to relax significantly — if not outright reverse — its damaging effects.

Relaxing or removing the embargo should be part of gradual diplomacy: As the Cuban government begins to restore political, economic and civil liberties to its people, the United States should loosen its economic sanctions.

Cuba is not the socialist paradise that Fidel Castro promised. He created a police state that represses free speech, free elections and the ability to accumulate personal wealth. It may be, as Mr. Castro boasts, that no Cuban lacks the basics of life. But most of them don’t have much more than that.

Although a U.S. president can ease travel and cultural exchanges via executive order, it would take congressional action to end sanctions imposed by the 1996 Helms-Burton Act. That’s long been regarded as political suicide in Florida, a key electoral state. But a recent Florida International University poll found that a majority of the Cubans in Miami-Dade County support normalizing relations with Cuba and lifting the economic embargo.

About 35 percent of the Cubans in South Florida broke ranks with the Republican party to vote for Mr. Obama, a Democrat. His support was especially strong among younger Cuban-American voters, many of whom don’t share the animosities of their fathers and mothers.

Lifting the embargo would be in the best interests of the United States in several ways:

• Economic. Although Cuba is just a blip on the global economic radar, it is a mere 90 miles from Florida and offers new markets to U.S. farmers and businesses.
• Strategic. Lifting the embargo would reestablish U.S. credibility throughout the Caribbean, Central and South America. It would deflect Cuba’s public flirtations with Russia, China and Venezuela.
• Brainpower. Cubans are poor but well-educated and literate at levels above other developing Latin American countries. It offers a trove of doctors and teachers, as well as a population hungry for access to the democratizing effects of the Internet, cell phones and personal technology.
• Humanitarian. Two generations of families in both countries have been tormented and divided. Families should be reunited, and Americans should be allowed to enjoy the ecological and cultural splendor of the island.

Cuba poses no direct military threat; the memories of the Bay of Pigs attack in 1961 and the missile crisis of 1962 are just that: memories.

The blockade serves only the interests of Cuba’s leaders. They can — and do — blame the many failings of a 50-year communist regime on what they call El Bloqueo. In many respects, the Castro revolution has survived not despite U.S. opposition, but because of it.

The best ambassadors for democracy in Cuba are American tourists, American businesses and American cultural representatives. The Cuban people may have been isolated from the world for 50 years, but they are smart and pragmatic. The United States should reach out to them, not only in their interest, but also in our own.