By 1840, a trans-Atlantic anti-slavery movement, led by free Black people from Boston to Baltimore, challenged America’s foundational economic and political system.  Yet, by the end of the decade, and despite an economic depression in 1837 that caused a temporary decline in profits from domestic slave trading, slavery led to a realignment of the American political system, the annexation of Texas, and increased sectional conflict between slave holding and non-slaveholding states.  Ideological and political conflict between so-called Cotton and Conscience Whigs prompted a shift in the country’s Party system, which was exacerbated by the Mexican-American War (1846 - 1848).  Meanwhile, Black abolitionists like Frederick Douglass (c. 1815 - 1895), Henry Highland Garnet (1815 - 1882) and Frances Ellen Watkins (1825 - 1911), many of whom were formerly enslaved, challenged American assumptions about race, freedom, and Black humanity.  Although nearly 2.5 million African descended people lived in the United States, only 390,000 of them were free. Data Source: US Census Records.