[Larry Lucido]

Could be one or two Civil War brides left.

[packrat35]

Helen Viola Jackson (August 3, 1919 – December 16, 2020) was the last surviving widow of a Union soldier and the last surviving widow of a Civil War veteran overall; she died on December 16, 2020, at the age of 101.
...
Helen Viola Jackson (1919–2020)

[packrat35]

Last American Revolution widow died in the 20th century.
https://en.wikipedia.org/wiki/Esther_Sumner_Damon