Caroline Love Goodwin O'Day (June 22, 1869 – January 4, 1943) was an American politician. She was the third woman, and first woman Democrat, elected to Congress from New York.
She graduated from Lucy Cobb Institute in Athens, Georgia. She studied art in Paris, Munich, and Holland. On April 20, 1901, she married Daniel O'Day. He was secretary and treasurer of Standard Oil Company.
She was President of the Rye School Board. She was a commissioner of the State Board of Social Welfare from 1923 to 1934.
She was vice chairwoman of the New York State Democratic Committee from 1916 to 1920, and Associate Chairwoman from 1923 to 1942. She was a delegate to the 1924, 1928, 1932 and 1936 Democratic National Conventions.
In 1934, 1936, 1938 and 1940, O'Day was elected at-large as a Democrat to the 74th, 75th, 76th and 77th United States Congresses, holding office from January 3, 1935, to January 3, 1943. While in the House she was Chairwoman of the Committee on Election of President, Vice President, and Representatives (75th through 77th Congresses). Among the legislation she sponsored or co-sponsored was the Wagner-O'Day Act, the predecessor to the Javits-Wagner-O'Day Act.
She was buried at the Kensico Cemetery in Valhalla, New York.
The United States Post Office – Rye was renamed the Caroline O'Day Post Office on October 23, 2010 in recognition of her public service.