The lowering of the Spanish flag and the hoisting of the U.S. flag was a ritual of ownership, signifying the transition to U.S. sovereignty. It was the clearest symbol of U.S. territorial expansion. This flag is a relic of that ritual. 

In the weeks surrounding the invasion of Puerto Rico, this flag was raised by the U.S. military at
Las Cabezas de San Juan lighthouse on the island’s northeastern town of Fajardo. With its forty-five stars representing the number of states at the time, the flag raised the question as to whether or not Puerto Rico and other lands now under that same flag would eventually become states in the union. 

On April 2, 1900, reflecting on the “new possessions,” Wisconsin Senator John C. Spooner asked, “Does the Constitution follow the flag?” This notion became central to the Supreme Court’s Insular Cases as the United States defined how it would administer the new territories.