Final answer:
The Netherlands was the first country to legalize same-sex marriage in 2000, preceding the legalization of same-sex marriage in the United States, which was not fully recognized nationwide until the Supreme Court's 2015 decision in Obergefell v. Hodges.
Step-by-step explanation:
The first country to legalize same-sex marriage in 2000 was the Netherlands. This marked a significant milestone in the global movement towards marriage equality. Even though other places like Vermont in the United States began creating legal frameworks for civil unions around the same time, it was the Netherlands that first extended the full status of marriage to same-sex couples at a national level. As for the United States, it wasn't until 2004 that Massachusetts became the first state to recognize same-sex marriages, with the Supreme Court eventually making same-sex marriage legal nationwide through the decision in Obergefell v. Hodges in 2015.