The June 1 Democratic presidential primary in Puerto Rico attracted only 387,299 voters. Puerto Rico has 2,366,667 registered voters. Normally Puerto Rican elections have a higher turnout than a typical U.S. state does. For example, in November 2004, 1,959,108 votes were cast for Puerto Rico’s non-voting Delegate to the U.S. House (Puerto Rico’s Delegate is called Resident Commissioner, and this office is elected every four years; it is not up in mid-term years).
This 16.4% turnout may have been low because Puerto Ricans who support independence promoted a boycott of the primary. On election day, 10,000 Puerto Ricans demonstrated for independence.
Puerto Rico’s Democratic presidential primary in 1980 attracted 886,280 voters. The Puerto Rican elections authorities printed 1,800,000 Democratic ballots for the June 1, 2008 primary, almost five times as many as were needed.
The poor turnout was a setback for Hillary Clinton, who had campaigned much more in Puerto Rico than Barack Obama had. She had been hoping for a massive turnout. Given her 68.4% victory in Puerto Rico, if Puerto Rico had had a huge turnout, she would have then been able to unambiguously say that she had received more popular votes in the whole country that Obama has received in the whole country. But given the low turnout, her margin in Puerto Rico was only 141,662.