Thanksgiving 2015: When is the national holiday and what is it all about?

The annual celebration of food, family and friends is nearly upon us, marking the start of the holiday season in the United States. Thanksgiving is a time when Americans gather together to eat turkey, pumpkin pie and watch football, traditions which have been adopted across the pond by Brits and expats - but where did the holiday originate, and why so much turkey?

When is Thanksgiving?

The holiday falls on the fourth Thursday of November, which this year is Thursday 26. It was not until President Abraham Lincoln's 1863 Proclamation that Thanksgiving was regularly commemorated each year on the last Thursday of November.

In 1939, however, the last Thursday in November fell on the last day of the month. Concerned that the shortened festive shopping season might hamper economic recovery, President Franklin D. Roosevelt moved Thanksgiving to the second to last Thursday of November, but 16 states refused to accept the change and proclaimed Thanksgiving to be the last Thursday in November.

For two years two days were celebrated as Thanksgiving - the President and part of the nation celebrated it on the penultimate Thursday in November, while the rest of the country celebrated it the following week. To end the confusion, Congress decided to set a fixed-date for the holiday. In 1941, the House passed a joint resolution declaring the last Thursday in November as the official Thanksgiving Day.

What is the history behind Thanksgiving?

Thanksgiving in America dates back to the 1600s. In 1621, the Plymouth colonists and Wampanoag Native Americans shared an autumn harvest widely believed to be one of the first celebrations of the holiday. It was to celebrate a successful growing season, as the harvests in the previous year had failed and many of the pilgrims had starved to death. Members of the Wampanoag tribe taught the pilgrims, who were weakened by malnutrition, how to cultivate corn, fish in the rivers and extract sap from maple trees.

The most popular Thanksgiving food is now turkey, often a centrepiece of the meal. Americans consume as many as 45 million turkeys every year at Thanksgiving, largely attributed to the history of the first Thanksgiving – when Governor Bradford's description of the pilgrims' first autumn in Plymouth stated: "There was a great store of wild turkeys, of which they took many, besides venison, e.t.c."

What is the history behind the Macy's Thanksgiving Parade?

Every year, the Macy's Thanksgiving Day Parade takes centre-stage in New York City, with enormous balloons, a pageant of floats and marching bands. The tradition started in 1924, when many employees at Macy's department store were first-generation immigrants and wanted to celebrate their new American holiday of Thanksgiving with the type of festivals celebrated in Europe. The staff dressed in costumes and travelled with Central Park zoo animals and creative floats for six miles, from Herald Square to Harlem in Manhattan.

As millions celebrate the holiday with family and friends, more than 8,000 people will take part in the parade – travelling through Manhattan to the catchphrase: "Let's have a parade." More than 3.5 million people turn up to watch the parade and over 50 million watch on the television.