Which event does Thanksgiving celebrate in the United States?

Thanksgiving in the United States primarily celebrates the harvest season. This holiday originated from the early 17th century when English Pilgrims celebrated their successful harvest in 1621, which is often recognized as one of the first Thanksgiving feasts. They gathered with Native Americans, who helped them cultivate the land, to give thanks for the bountiful harvest and the survival of their community during the harsh winter months that followed.

This focus on gratitude for the harvest is central to the Thanksgiving tradition, where families and friends come together to enjoy a meal featuring seasonal foods, symbolizing an abundant harvest. The holiday has evolved over the years but continues to embody themes of thankfulness and fellowship centered around the fruits of the earth.

The other options are based on significant historical events that do not align with the roots of Thanksgiving. The founding of the first colony and the signing of the Declaration of Independence represent distinct moments in American history unrelated to this celebratory harvest aspect. Similarly, the end of the Civil War marked a crucial turning point in U.S. history but also does not connect directly to the essence of the Thanksgiving celebration.