I've been on an early US feminist history kick lately, and based on what I've read, it's more nuanced than saying Black women were systematically excluded. For example, in the famous incident of Ida B. Wells and black suffragettes being told to march at the back of the Woman Suffrage Procession, Virginia Brooks and Belle Squire both offered to march with Wells at the back. When Wells joined the IL delegation out of the crowd, Brooks and Squire linked arms with her to demonstrate racial solidarity and universalism. Alice Paul, the main organizer, was supportive of Black women marching, but was also willing to segregate the march to placate some of the Southern suffragettes.

And in a lot of ways, that experience captures the development/schisms of the US suffragette movement over time as a whole. Many of the initial white suffragettes were abolitionists who worked in partnership with Black women and men and saw the two causes as linked. Black women organized and were part of the US suffragette movement as a whole. But as Southern overt white supremacy became a clear political obstacle, there were schisms around how to negotiate that political reality. Women weren't always organizing together across racial lines.