December 18, 1777 marked the first time that all 13 colonies joined in a thanksgiving celebration. It commemorated the patriotic victory over the British at Saratoga: 

"It is therefore recommended by Congress, that Thursday the 18th. day of December next be set apart for Solemn Thanksgiving and Praise; that at one time, and with one voice, the good people may express the grateful feelings of their hearts, and consecrate themselves to the service of their divine benefactor; and that, together with their sincere acknowledgements and offerings they may join the penitent confession of their sins; and supplications for such further blessings as they stand in need of." 

President George Washington proclaimed a National Day of Thanksgiving for November 26, 1789 to honor the formation of the United States government. His proclamation called for a day of prayer and giving thanks to God. It was to be celebrated by all religious denominations, but discord among the colonies prevented it from being practiced by all the states. Washington wrote in his November 26th diary entry: "Being the day appointed for a thanksgiving I went to St. Paul's Chapel though it was most inclement and stormy--but few people at Church." President Washington later provided money, food, and beer to debtors spending the holiday in a New York City jail.

Thanksgiving failed to become an annual tradition at this time. Only Presidents Washington, Adams, and Madison declared national days of thanks in their terms. Thomas Jefferson and John Quincy Adams considered the practice to infringe upon the separation of church and state. During the War of 1812, President Madison proclaimed three days of fasting and prayer in response to Congressional requests (August 20, 1812, September 9, 1813, and January 12, 1815). He was the last president to call for a national thanksgiving until Abraham Lincoln in 1863. Governors, on the other hand--particularly in the New England states, regularly issued proclamations of thanksgiving.

How did Thanksgiving become a yearly national practice?

It was Sarah Josepha Hale, a magazine editor, whose efforts eventually led to what we recognize as Thanksgiving. Hale wrote many editorials championing her cause in her Boston Ladies' Magazine, and later, in Godey's Lady's Book. She was fired with the determination of having the whole nation join together in setting apart a national day for giving thanks "unto Him from who all blessings flow."

In 1830, New York proclaimed an official state "Thanksgiving Day." Other states soon followed its example. The Territory of Minnesota celebrated its first Thanksgiving Day on December 26, 1850. The whole territory, including all of what is now the State of Minnesota plus the Dakotas as far west as the Missouri River, contained approximately 6,000 settlers but the book, The Frontier Holiday, describes a spirited celebration. Territory Governor, Alexander Ramsey, proclaimed the day of thanks:

"Young in years as a community, we have come into the wilderness, in the midst of savage men and uncultivated nature to found a new empire in aid of our pursuit of happiness, and to extend the area of enlightened republican Liberty . . . . Let us in the public temple of religion, by the fireside and family altar, on the prairie and in the forest, join in the expression of our gratitude, of our devotion to the God who brought our fathers safely through the perils of an early revolution, and who thus continues his favors to the remotest colonies of his sons."

By 1852, Hale's campaign succeeded in uniting 29 states in marking the last Thursday of November as "Thanksgiving Day."

Finally, after a 40-year campaign of writing editorials and letters to governors and presidents, Hale's passion became a reality. On September 28, 1863, Sarah Josepha Hale wrote a letter to President Lincoln and urged him to make Thanksgiving a national fixed festival. In 1863, President Lincoln proclaimed the last Thursday in November as a national day "of Thanksgiving and Praise to our beneficent Father." Here is part of the text of Lincoln's proclamation:

We have been the recipients of the choicest bounties of heaven. We have been preserved, the many years, in peace and prosperity. We have grown in numbers, wealth and power, as no other nation has ever grown. But we have forgotten God. We have forgotten the gracious hand which preserved us in peace and multiplied and enriched and strengthened us; and we have vainly imagined, in the deceitfulness of our hearts that all these blessings were produced by some superior wisdom and virtue of our own.

Intoxicated with unbroken success, we have become too self-sufficient to feel the necessity of redeeming and preserving grace, too proud to pray to God that made us! It behooves us, then to humble ourselves before the offended Power, to confess our national sins, and to pray for clemency and forgiveness. 

I do therefore invite my fellow citizens in every part of the United States, and also those who are at sea and those who are sojourning in foreign lands, to set apart and observe the last Thursday of November next, as a day of Thanksgiving and Praise to our beneficent Father who dwelleth in the Heavens.

-- April 30, 1863, President Abraham Lincoln's Proclamation for a National Day of Fasting, Humiliation and Prayer 

Lincoln issued a similar proclamation in 1864. U.S. presidents maintained the holiday on the last Thursday of November for 75 years (with the exception of Andrew Johnson designating the first Thursday in December as Thanksgiving Day 1865 and Ulysses Grant choosing the third Thursday for Thanksgiving Day 1869).

In 1939, President Franklin Delano Roosevelt declare the next-to-last Thursday of the month (November 23rd) to be Thanksgiving Day. This break with tradition was prompted by requests from the National Retail Dry Goods Association. Since 1939 had five Thursdays in November, this would create a longer Christmas shopping season. While governors usually followed the president's lead with state proclamations for the same day, on this year, twenty-three states observed Thanksgiving Day on November 23rd, the "Democratic" Thanksgiving. Twenty-three states celebrated on November 30th, Lincoln's "Republican" Thanksgiving. Texas and Colorado declared both Thursdays to be holidays.

After two years of public outcry and confusion, Congress introduced the legislation to ensure that future presidential proclamations could not impact the scheduling of the holiday.. They established Thanksgiving Day as the fourth Thursday in November. The legislation took effect in 1942. Their plan to designate the fourth Thursday of the month allowed Thanksgiving Day to fall on the last Thursday five out of seven years. 

Thanksgiving and Christians

There are those who want to remove any thought of God from our Thanksgiving celebrations. They wish to secularize the holiday and they reinvent history to attempt to prove their point. But it is evident from reading primary sources that Thanksgiving in America was always about giving thanks to God.

It is a Christian command and privilege to be grateful for the blessings of God (Deuteronomy 8:10; Psalm 107:19,21; Colossians 1:12-14; Philippians 1:3). Our Thanksgiving celebration is a wonderful reminder to "give thanks to the Lord, for He is good. His love endures forever" (1 Chronicles 16:34).

The Rev. Benjamin Arnett was a prominent African American cleric in the Ohio AME Church. He preached a Thanksgiving sermon during the centennial of our nation on November 30, 1876. His sermon is a beautiful expression of gratitude to God for national blessings and a call to continue to pursue righteousness for ourselves and our nation (Proverbs 14:34): 

Following the tracks of righteousness throughout the centuries and along the way of nations, we are prepared to recommend it to all and assert without a shadow of doubt, that 'Righteousness exalted a nation'; but on the other hand following the foot-prints of sin amid the ruins of Empires and remains of cities, we will say that 'sin is a reproach to any people.' But we call on all American citizens to love their country, and look not on the sins of the past, but arming ourselves for the conflict of the future, girding ourselves in the habiliments of Righteousness, march forth with the courage of a Numidian lion and with the confidence of a Roman Gladiator, and meet the demands of the age, and satisfy the duties of the hour. 

Let us be encouraged in our work, for we have found the moccasin track of Righteousness all along the shore of the stream of life, constantly advancing holding humanity with a firm hand. We have seen it 'through' all the confusion of rising and falling States, of battle, siege and slaughter, of victory and defeat; through the varying fortunes and ultimate extinctions of Monarchies, Republics and Empires; through barbaric irruption and desolation, feudal isolation, spiritual supremacy, the heroic rush and conflict of the Cross and Crescent; amid the busy hum of industry, through the marts of trade and behind the gliding keels of commerce.

And in America, the battle-field of modern thought, we can trace the foot-prints of the one and the tracks of the other. So let us use all of our available forces, and especially our young men, and throw them into the conflict of the Right against the Wrong. 

Then let the grand Centennial Thanksgiving song be heard and sung in every house of God; and in every home may thanksgiving sounds be heard, for our race has been emancipated, enfranchised and are now educating, and have the gospel preached to them!

"Thank you"  to Dennis Rupert for this true story of Thanksgiving
New Life Ministries

Resources:

1 Of Plimoth Plantation by William Bradford, original manuscript, written 1647, (1901 Edition)

2 Edward Winslow's letter, written December 11, 1621.

3 Edward Winslow's letter, written December 11, 1621.

4 William Bradford's comments about the harvest from Of Plimoth Plantation by William Bradford.

5 Of Plimoth Plantation by William Bradford, original manuscript, written 1647, (1901 Edition)