“Coming together is a beginning; keeping together is progress; working together is success” is a popular saying of uncertain authorship. U.S. President Calvin Coolidge said in 1927:
 
“Edward Everett Hale said: ‘Together—one of the most inspiring words in the English language. Coming together is a beginning; keeping together is progress; working together is success.’”
 
American author Edward Everett Hale (1822-1909) is frequently credited in most all of the early citations, but it’s not known where he wrote this. American industrialist Henry Ford (1863-1947) has been credited with the saying since at least 1949, but there is no evidence to suggest that he either originated or popularized it.
 
   
11 June 1927, Charleston (WV) Gazette, “Treasury Surplus Is of Doubtful Value Says Coolidge in Address,” pg. 8, col. 1:
At the budget meeting of the United States government held in Washington, June 10, 1927, at 8 o’clock p.m., President Coolidge spoke as follows:
(...) (Col. 7)
Working Together
Edward Everett Hale said: “Together—one of the most inspiring words in the English language. Coming together is a beginning; keeping together is progress; working together is success.”
(The full text is also in Google Books.—ed.)
 
13 September 1930, The Morning Star (Rockford, IL), “Quotations,” pg. 4, col. 3:
“Together, the most inspiring word in the English language. Coming together means beginning, keeping together means progress, working together means success.”
—Edward Everett Hale.
 
30 August 1931, The Salt Lake Tribune (Salt Lake City, UT), “The Senator from Sandpit,” pg. 2C, col. 7:
“Coming together is a beginning; keeping together is progress; working together is success.”
 
30 April 1933, Monroe (LA) Morning World, “Society: Importance of Educating Our Children Stressed By National P. T. A. Officer,” pg. 9, col. 3:
“Who said, ‘Together,’ is the most beautiful word in the English language. I love it too.
 
“Coming together is a beginning,
Keeping together is progress,
Thinking together is unity,
Working together is success.”
 
6 March 1937, Denton (TX) Journal, “Homemaker Clubs,” pg. 5, col. 5:
Coming together is a beginning,
Thinking together is Unity;
Keeping together is progress,
Working together is success.
 
5 August 1949, Harper (TX) Herald, pg. 2, col. 4:
Coming together is a beginning; keeping together is progress; working together is success. 
—Henry Ford
 
Google Books
Introducing Leadership:
A Practical Guide
By Alison Price and David Price
London: Icon Books Ltd.
2013
Pg. ?:
Coming together is a beginning. Keeping together is progress. Working together is success. – Henry Ford