Which three of the new slave states were most important to the growth and expansion of slavery How can you tell?

The three most important new slave states for the growth and expansion of slavery were Alabama, Mississippi, and Louisiana. These states were situated in the Deep South and had fertile land suitable for cash crops like cotton and sugar, which heavily relied on slave labor. The rapid increase in plantation agriculture in these regions during the 19th century led to a significant rise in the demand for enslaved people. Additionally, the establishment of the cotton gin and the expansion of the domestic slave trade further entrenched slavery in these states, making them pivotal to the institution's growth in the United States.