|Centuries:||17th century – 18th century – 19th century|
|Decades:||1740s 1750s 1760s – 1770s – 1780s 1790s 1800s|
|Years:||1775 1776 1777 – 1778 – 1779 1780 1781|
- The term thoroughbred was first used in the United States in an advertisement in a Kentucky gazette to describe a New Jersey stallion called Pilgarlick.
- January 18 – Third Pacific expedition of Capt. James Cook, with ships HMS Resolution and HMS Discovery, first see O'ahu then Kaua'i in the Hawaiian Islands, which he names the "Sandwich Islands".
- February 5 – South Carolina becomes the first state to ratify the Articles of Confederation.
- February 6 – American Revolutionary War: In Paris the Treaty of Alliance and the Treaty of Amity and Commerce are signed by the United States and France beginning official recognition of the new republic.
- February 23 – American Revolutionary War: Baron von Steuben arrives at Valley Forge, Pennsylvania and begins to train the Continental Army.
- July 10 – American Revolutionary War: Louis XVI of France declares war on the United Kingdom of Great Britain.
- July 27 – American Revolution: First Battle of Ushant – British and French fleets fight to a standoff.
- August 26 – Triglav, at 2,864 metres above sea level the highest peak of Slovenia, was ascended for the first time by four brave men: Luka Korošec, Matevž Kos, Štefan Rožič and Lovrenc Willomitzer on Sigismund Zois's initiative.
- September – The Massachusetts Banishment Act, providing punishment for Loyalists, is passed.
- November 26 – In the Hawaiian Islands, Captain James Cook becomes the first European to discover Maui.
- France introduced the first state-controlled brothel.
- The first settlement was made in the area of what is now Louisville, Kentucky by 13 families under Col. George Rogers Clark.
- Phillips Academy, the most prestigious secondary boarding school in the United States, was founded by Samuel Phillips Jr.
- for more information, see Category:1778 births.
- for more information, see Category:1778 deaths.