Answer:
Elizabeth Stanton is referring to the American Independence Day of 4th July.
Step-by-step explanation:
Elizabeth Stanton wrote this letter to Lucretia Mott on July 19, 1876. The issue of the letter was mainly about women's rights and their work on gaining equality with men. Stanton expresses her utter frustration and disbelief in the many years it has taken them to fight for their rights and still not be given any fruitful result.
In her letter, she mentioned how "the long, weary years of waiting and hoping without success" had made them believe that there is no "faith and hope to continue the work". She laments how the rulers of the country could not see the issue as important and that it might take so many more years to be able to see the fruits of their long struggle. She concluded the letter with the words "May we now safely prophecy justice, liberty, equality for our daughters ere another centennial birthday shall dawn upon us".
The centennial birthday she is referring to in this letter is the American declaration of Independence Day of July 4th.