What was one significant action taken by Abraham Lincoln?

One significant action taken by Abraham Lincoln was the Emancipation Proclamation, which declared that all enslaved people in the Confederate states were to be set free. By issuing this executive order in 1863, Lincoln took a crucial step towards ending slavery in the United States. This action not only aimed to weaken the Confederacy during the Civil War but also helped shift the focus of the war towards the broader goal of human rights and liberty.

The other options do not accurately reflect Lincoln's contributions. For instance, he did not sign the Constitution; that document was adopted in 1787, long before his presidency. While he did support some civil rights initiatives, his most notable and direct action concerning civil rights was the emancipation of enslaved individuals. The establishment of the Federal Reserve occurred in 1913, after Lincoln's time, eliminating that option as relevant to his actions.