From the 1973 Joint Resolution: “Resolved by the Senate and House of Representatives of the United States of America in Congress assembled, That August 26, 1973, is designated as ‘Women's Equality Day’, and the President is authorized and requested to issue a proclamation in commemoration of that day in 1920 on which the women of America were first guaranteed the right to vote. Approved August 16, 1973.”
 

From The American Presidency Project, 1973 Proclamation 4236—Women's Equality Day: 

“Fifty-three years ago, on August 26, 1920, the Nineteenth Amendment was certified as part of our Constitution, assuring that ‘the right of citizens of the United States to vote shall not be denied or abridged by the United States or by any State on account of sex.’"

“The struggle for women's suffrage, however, was only the first step toward full and equal participation of women in our Nation's life. In recent years, we have made other giant strides by attacking sex discrimination through our laws and by paving new avenues to equal economic opportunity for women. Today, in virtually every sector of our society, women are making important contributions to the quality of American life.”