VIGO, Spain — Before the holiday season, the mayor of this Spanish city bragged that his Christmas lights would outshine New York, which lies across the Atlantic on the same latitude.

Holding up his cellphone at a news conference, Vigo’s mayor, Abel Caballero, jokingly predicted that he would soon get a call from his counterpart, Bill de Blasio, telling him that New Yorkers were feeling jealous because they could see that “the lights of Vigo are the best on the planet.”

New York’s mayor did not ring him. But tens of thousands of visitors have since responded to Mr. Caballero’s invitation, generating a Christmas tourism boom that has been a welcome change for Vigo. The city’s claim to fame in other seasons is as an industrial hub and Spain’s largest fishing port.

Mr. Caballero, 73, is an exuberant Socialist politician who also likes to call himself “the most popular mayor in Europe.” Still, some have wondered whether the mayor’s almost unparalleled enthusiasm for Christmas lights has gone over the top, giving him a certain notoriety in Spain.