Final answer:
The exact membership number for the National Farmers' Alliance in 1964 is not provided in the given references, but historically, the Colored Farmers' National Alliance had reached a peak of a million members, and the broader Farmers' Alliance had over 2.5 million members in the early 1890s.
Step-by-step explanation:
By 1964, the membership in the National Farmers' Alliance, which included the Colored Farmers' National Alliance, had reached a significant number several decades earlier. However, specific membership numbers for 1964 are not given in the provided references, making it difficult to provide an exact figure. It is important to note that the Colored Farmers' National Alliance, which was established in 1886 due to exclusionary policies, grew quickly to have as many as a million members at its peak. The earlier Farmers' Alliance, a broader organization including all regional alliances, had over 2.5 million members by the early 1890s, reflecting the unity among farming communities despite racial tensions.