In order to know which amendment gave women the right to vote, you will first need to understand as to why a special amendment was needed for women to enforce this universal and fundamental right. There was a time when women all over the world, had no rights and were not recognized as either individuals or citizens. They had no identity of their own, not even under a Democracy.
It was only during the end of the 18th century that things began to change, the genesis of women's suffrage originated from France, as more and more women began demanding for their basic fundamental rights. The concept of women's suffrage meant that women be allowed to vote, be elected for governmental offices, that they may be treated equally without any discrimination on the grounds of sex, and that they may not be restricted or disqualified on socioeconomic grounds. This was a revolutionary reform movement aimed at realizing the right to equality and life for women, and would become an important event in American history.
Women's World Suffrage
Though America was one of the late bloomers to introduce women's suffrage in its Constitution, this reform movement had already spread and become popular in Europe and their colonies across the globe. The revolution which initiated the women's suffrage, began to bear fruits from 1893 onwards. It started from the British colony in New Zealand, which was the first nation to allow its women to vote. However, they were not allowed to run for office until 1919. Soon, this reform was imbibed by Australia in 1895 and they allowed complete representation to their women as citizens and prospective candidates for all public offices. Thereafter, the Grand Duchy of Finland and some autonomous countries of the Russian Empire elected their first women parliamentary members in the year 1907.
The Amendment for Women to Vote
The Nineteenth Amendment (August 18, 1920) of the USA says - "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. Congress shall have power to enforce this article by appropriate legislation."
President Woodrow Wilson was the only US President, who officially declared his support for women's right to vote and its amendment on January 9th, 1918. The House of Representatives could not pass the amendment because the Senate refused to debate the bill until October. The movement was led by the National Women's Party, who asked the pro-suffrage citizens to desist from voting and supporting these senators. That year the anti-suffrage senators could not manage to get reelected against the Congress, which was known to be a majority pro-women's suffrage. The bill for amendment was passed between May and June of 1919 by both the House of Representatives as well as the Senate.
Ratification of The Women's Bill
The United States of America ratified women's voting rights on August 18, 1920, through its 'Nineteenth Amendment' (XIX). This amendment specifically prohibited all the federal governments and all the States from discriminating or denying the right to vote on the grounds of the citizen's sex. The 19th amendment in the Constitution was the first of its kind. It became an integral part of the 'Bill of Rights' and gave women the right to a good college education and graduation degree, to take up subjects of their personal choice, freedom from unemployment, freedom to own businesses and work in companies, right to become members of the House of Representatives, and run for office to become Senators. This was the stepping stone for women's political emancipation in America.
Universal Declaration of Human Rights
It was one of the declarations by the United Nations that finished the world's confusion and agitation over equality and equity between men and women. The universal declaration of human right was adopted by all its members in 1948. Thereafter, in 1979, the Convention on the Elimination of All Forms of Discrimination against Women (CEDAW) was adopted by the UN General Assembly.
The world has seen many positive changes since these laws were introduced and many women have since, risen to play powerful executive roles for various governmental positions.