By the start of the French and Indian War in 1754, Delaware had already been an English colony for ninety years. It was not included in the Albany Plan of Union, which was proposed by some American colonists the same year. However, the colony did participate in the First and Second Continental Congresses. Delaware approved the Declaration of Independence on 2 July 1776. In August and September of that year, Delaware wrote its own constitution. During the Revolutionary War, Delaware was the site of one minor battle. On 3 September 1777, Delaware militia attacked English soldiers marching to Philadelphia at the Battle of Cooch's Bridge.
After independence, Delaware ratified the Articles of Confederation in 1779 and became the first state to ratify the federal Constitution, doing so on 7 December 1787. Between 1790 and 1830, Delaware's population grew by nearly 30 percent. In 1790, the total population was 59,096. In succeeding decennial censuses, the total state population increased from 64,273 in 1800 to 72,674 in 1810 to 72,749 in 1820 to 76,748 in 1830. Though a slave state, Delaware's free black population increased from 3,899 to 15,855 in the forty years between 1790 and 1830, while the number of slaves decreased from 8,887 to 3,292 over the same duration. The latter trend is partially explained by the state constitution's prohibition on importing slaves into the state and by the presence of active abolition societies, which were first established in Dover and Wilmington in 1788.
Native Americans inhabited the Delaware area for hundreds of years before European migration. Although there was some presence of the Nanticoke tribe, the largest American Indian population included members of the Lenape group, later renamed the Delaware by European settlers. Delaware Indians in fact comprised three groups, the Munsee, the Unalachtigo, and the Unami. William Penn signed a treaty of friendship with the Delaware confederation in 1682. Later, however, other tribes and the English forced the relocation of most Delaware Indians to areas west of the Mississippi River.
The growth of political parties in Delaware was shaped by the personalities of leaders, contentious issues of the era, and by the development of national parties. Prior to the founding of the Democratic Party, Delaware strongly backed Federalist candidates. Between 1789 and 1828, Delaware voters elected ten Federalist and three Democratic Republican governors. At the presidential level, state electors endorsed Federalist candidates in every election until 1820, when James Monroe outpolled John Quincy Adams.