How close to a 51st star on the flag?

Americans are not famous for their knowledge of other lands.

So it may come as a surprise to many that a small island in the Caribbean, more than 1,000 miles southeast of Miami, will vote Sunday on whether to become the 51st US state.

More than 2 million people in Puerto Rico, a strategically important gateway to the Caribbean seized by the United States 100 years ago during the Spanish-American War, will seek for the third time an end to their lingering national limbo.

For decades this quasi-colony has existed as a US "commonwealth" - a sort of halfway house of Americanness devised in 1952. But this year, for the first time, it appears the faction intent on adding another star to the US flag will win most of the votes.

While the plebiscite can be ignored by Congress - which in the end decides whether Puerto Rico should be allowed into the Union - a victory for pro-statehood Puerto Ricans would add weight to their long call for Washington's full embrace.

"There's little question that Puerto Rico is moving in the direction of statehood," says Robert Pastor, a political scientist from Harvard University in Cambridge, Mass., who specializes in Caribbean studies. "But it's very simple. As a nation, the United States' people have not thought about this issue. Congress hasn't even thought about this issue - other than less than a dozen congressmen and senators."

Indeed, many Americans, asked what they think of Puerto Rico becoming the 51st state, respond with a nonplussed shrug followed by an admission of ignorance about the issue.

There are few shrugs of ignorance or apathy here, though. The island's political parties have spent more than $2 million in bombarding Puerto Rican voters with their messages. And some 73 percent of the island's 2.2 million registered voters are expected to vote Sunday.

The choices

When residents go to the polls, they have five options:

* Continue as a commonwealth.

* Become a US state.

* Independence.

* "Free association," essentially independence with treaty ties to the United States similar to former US territories such as the Marshall Islands and Palau.

* None of the above.

A poll published on Dec. 9 by The San Juan Star, a leading local daily newspaper, indicated 49 percent of the electorate will vote for statehood and 45 percent will choose the "none of the above" option. In protest of what they consider unfair wording of the ballot, the traditional advocates of commonwealth are boycotting the plebiscite and telling their supporters to vote "none of the above."

Independence has never been a real issue for most Puerto Ricans, who have little interest in giving up their much-coveted US citizenship. Residents have carried US passports since 1917, but they can't vote for president or Congress - unless they are one of nearly 3 million Puerto Ricans living on the US mainland.

Under commonwealth status Puerto Rico has blended the trappings of sovereignty with the airs of statehood. While the United States provides up to $10 billion a year in federal aid to Puerto Rico and tens of thousands of Puerto Ricans have fought in wars for the US, islanders don't pay federal taxes and keep symbols of autonomy such as an Olympic team.

Anti-statehood advocates have drawn on symbols like these in an effort to sway the vote. The pro-commonwealth faction aired an ad implying statehood would mean the end of Puerto Rico's separate Olympic team. During the spot, an anonymous hand rips the Puerto Rico logo off a basketball player's jersey.

Yet statehood proponents note that US investments have boosted annual per capita income here to $8,500 - one- third the US average but five times higher than in nearby Dominican Republic, and the highest in Latin America. Still, 59 percent of residents on this island of 3.8 million people live below the US poverty line, according to the 1990 census.

And that's something that makes US policymakers less than exuberant about making Puerto Rico the next state. Another flash point is the issue of language. Some have warned that Puerto Rico - where fewer than one-third of the people speak English well and leaders insist statehood doesn't mean English would replace Spanish as the island's dominant language - could become the Quebec of the United States, referring to the restive French-speaking Canadian province.

"At some point folks in the US might wake up and say, 'Who are these peo-ple?' " says Ramon Daubon, a specialist on Puerto Rico for the Caribbean studies group at Georgetown University in Washington. "Puerto Rico is a poor state, the people are not white and not English-speaking. They also want a greater degree of self-government than most states."

Inevitability of statehood

Still, Mr. Daubon and others who have studied the issue believe Puerto Rico will eventually become a state, even if it takes a few decades. Islandwide votes on the issue have shown a slackening in appeal for commonwealth. In a 1952 vote on the island's Constitution, some 80 percent supported commonwealth. In the most recent plebiscite - in 1993 - commonwealth got only 49 percent.

In the end, even if statehood carries the day, the vote must be convincing to make people seriously consider the issue. A mere plurality is unlikely to impress Congress. Many members have said they would like to see at least a solid majority, if not two-thirds, voting in support of statehood before they take action.

"It's obvious, from many factors, that there will be a plurality for statehood," says Juan Garcia Passalacqua, a political analyst in Puerto Rico. "The real question now is what is Congress going to do. Do they want to admit a Hispanic state as the 51st state?"