A timeline of American history during this era should begin with the founding of the country, continuing on through the Louisiana Purchase and War of 1812. Taking the timeline to 1860 brings up the slavery issues that resulted in the Civil War.
An American history timeline from 1776 should begin with the signing of the Declaration of Independence in 1776, which severed ties with Great Britain and launched the Revolutionary War. After years of fighting, the Americans were eventually granted their freedom by treaty in 1783. The drafting of the Constitution in 1787 and its final ratification in 1789 turned the 13 breakaway colonies into the United States.
The timeline should travel through the growing pains experienced by the new nation. The Louisiana Purchase and related Lewis & Clark expedition in 1803 more than doubled the size of the country. The War of 1812 resulted in permanent boundaries between the United States and Canada and removed British and French influence from areas claimed by the Americans. The aftermath also contributed heavily to the displacement of Native American nations to reservations and non-controlled territories.
The timeline concludes with the rising regional split between Northern and Southern states over slavery. The Missouri Compromise of 1820 made Southern states slave states and Northern states free states. The Kansas-Nebraska Act in 1854 helped stoke the likelihood of armed conflict over self-determination and states' rights. The Dred Scott Case in 1857 stripped all human rights from American slaves, and the resulting outrage across the North became a tipping point that helped make the Civil War inevitable.