Final answer:
The inclusion of blacks and women in the National Labor Union in 1869 was influenced by the solidarity forged through shared struggles like the abolitionist movement, the labor movement's growing awareness of strength in unity post-Civil War, and economic and workforce changes that underscored the importance of labor unity and equal rights.
Step-by-step explanation:
The men of the National Labor Union (NLU) voted to include blacks and women among their numbers in 1869 because of several factors that raised social consciousness and a desire for equality. With changes post-Civil War, there was a growing recognition of the strength in unity, as evidenced by the battles fought together during the abolitionist movement and within social movements such as temperance and suffrage.
Furthermore, the economic and political changes of the era, which included the push for black suffrage during Reconstruction and the demand for labor that allowed women, especially black women, to form networks and advocate for equal pay, influenced the inclusion of women and black men in the labor movement.
The abolitionist movement played a critical role, where women's leadership and the participation of black men alongside women, laid a foundation for involving women and blacks in politics and in establishing their rights within the union movement.
Following the Civil War, the demand for labor unity became more pressing, and the National Labor Union saw the benefits of including groups who were actively seeking greater rights and representation, further influenced by the economic changes of the early 1880s when farmers began to see the benefits of labor unity.
Despite facing segregation and fewer opportunities, the wartime labor conditions and federal government positions also empowered black workers, including women, to seek fair treatment and equality in the workforce, which translated into more progressive attitudes within labor unions.