In 1909, she founded the Political Equality League to get votes for suffrage-supporting New York State politicians, wrote articles for newspapers, and joined the National American Woman Suffrage Association (NAWSA).

She was married twice, to socially prominent New York City millionaires William Kissam Vanderbilt, with whom she had three children, and Oliver Hazard Perry Belmont.

On "Equal Pay Day," April 12, 2016, Belmont was honored when President Barack Obama established the Belmont-Paul Women's Equality National Monument in Washington, D.C. Alva Erskine Smith was born on January 17, 1853, at 201 Government Street in Mobile, Alabama, to Murray Forbes Smith, a commission merchant,[clarification needed] and Phoebe Ann Desha.

Harold Stirling graduated from Harvard Law School in 1910, then joined his father at the New York Central Railroad Company.

He remained the only active representative of the Vanderbilt family in the New York Central Railroad after his brother's death, serving as a director and member of the executive committee until 1954.

"[7] Triumphant, Alva dressed as a venetian noble to the ball, but her sister-in-law Alice outdid her, in a costume highlighting a then brand-new invention: the electric light.

[7] The ball served as a catalyst to raise the bar on society entertainments in New York to heights of extravagance and expense that had not been previously seen.

William commissioned Richard Morris Hunt again, and the elaborate Marble House was built next door to Mrs. Astor's Beechwood.

[11] Alva's ostentatious displays of wealth helped to fuel American public interest in the lives of the rich and powerful, and, coupled with the opulent and decadent lifestyles by America's rich and their apparent disregard for the wellbeing of the working class, helped to also fuel fears that America had become a plutocracy.

[14] Upon Oliver's sudden death in 1908, Alva took on the new cause of the women's suffrage movement after hearing a lecture by Ida Husted Harper.

In 1909, she founded the Political Equality League to get votes for suffrage-supporting New York State politicians, and wrote articles for newspapers.

She paid the bail of picketers who had been arrested and funded a large rally in the city's Hippodrome, which she addressed along with Shaw, president of the National American Woman Suffrage Association (NAWSA).

In 1909 she joined this organization and was named an alternate delegate from New York to the International Women's Suffrage Association meeting in London.

[16]By this time, organized suffrage activity was centered on educated, middle-class white women, who were often reluctant to accept immigrants, African Americans, and the working class into their ranks.

[17] Working with leading clubwomen in the African American community, like S. J. S. Garnet, F. R. Keyser, Marie C. Lawton and Irene Moorman, she encouraged them to form a Black branch of her Political Equality League.

[18][19] She established its first "suffrage settlement house" in Harlem, and she included African American women and immigrants in weekend retreats at Beacon Towers, her Gothic style castle in Sands Point.

[4] The Congressional Union for Woman Suffrage (CU), originally led by Alice Paul and Lucy Burns, separated from the NAWSA in 1913.

At the same time, Belmont was funding Laura Clay's Southern States Woman's Suffrage Conference in Kentucky, because of her Alabama roots.

Belmont's daughter Consuelo, who promoted suffrage and prison reform in England, addressed the gathering, which was followed by the CU's first national meeting.

The following year, she and Paul established the National Woman's Party from the membership of the CU and organized the first picketing ever to take place before the White House, in January 1917.

The National Woman's Party continued to lobby for new initiatives from the Washington, D.C., headquarters that Belmont had purchased in 1929 for the group, which became the Sewall–Belmont House and Museum.

[4] On April 12, 2016, President Barack Obama designated Sewall–Belmont House as the Belmont–Paul Women's Equality National Monument, named for Belmont and Alice Paul.

With Paul, she formed the International Advisory Council of the National Woman's Party and the Auxiliary of American Women abroad.

She suffered a stroke in the spring of 1932 that left her partially paralyzed, and she died in Paris of bronchial and heart ailments on January 26, 1933.

[15][24] Her funeral at Saint Thomas Episcopal Church in New York City featured all female pallbearers and a large contingent of suffragists.

[28] Hunt was again hired to design the neoclassical style Marble House in Newport, Rhode Island, as William K. Vanderbilt's 39th birthday present and summer "cottage" retreat for Alva.

[30] Eager to reshape and redesign Belcourt, Alva made changes that transformed the interiors of the mansion into a blend of French and English Gothic and Renaissance styles.

Construction was still underway when Oliver Belmont died, when Alva announced that she would build an addition that was an exact reproduction of the Gothic Room in Belcourt, to house her late husband's collection of medieval and early Renaissance armor.

She also built a massive neo-Gothic portal gate on the northern entrance road, separating the château and village from the surrounding farmland.