The modern Thanksgiving holiday traces its origins from a 1621 celebration at the Plymouth Plantation, Massachusetts, where the Plymouth settlers held a harvest feast after a successful growing season. The first Thanksgiving feast lasted three days, and was attended by 53 Pilgrims and 90 Native Americans. The New England colonists were accustomed to regularly celebrating «thanksgivings» — days of prayer thanking God for blessings such as military victory or the end of a drought, though the 1621 events were likely not a religious observation.

Squanto, a Patuxet Native American who resided with the Wampanoag tribe, taught the Pilgrims how to catch eel and grow corn and served as an interpreter for them (Squanto had learned English while enslaved in Europe and during travels in England). Additionally the Wampanoag leader Massasoit had donated food stores to the fledgling colony during the first winter when supplies brought from England were insufficient.

The meal held in 1621 by the Wampanoag and the Pilgrims in Plymouth is continued in modern US with the Thanksgiving dinner. Certain kinds of food are traditionally served. Firstly, baked or roasted turkey is usually the featured item on any Thanksgiving feast table (so much so that Thanksgiving is sometimes referred to as «Turkey Day»). Stuffing, mashed potatoes with gravy, sweet potatoes, cranberry sauce, sweet corn, various fall vegetables (mainly various kinds of squashes), and pumpkin pie are commonly associated with Thanksgiving dinner. All of these are actually native to the Americas or were introduced as a new food source to the Europeans when they arrived.

Thanksgiving, or Thanksgiving Day, is celebrated in the United States on the fourth Thursday in November and has officially been an annual tradition since 1863, when, during the Civil War, President Abraham Lincoln proclaimed a national day of «Thanksgiving and Praise to our beneficent Father who dwelleth in the Heavens», to be celebrated on Thursday, November 26.