フォート・ハーマー条約(1789年)は、アメリカ合衆国とハウデノソーニー、オジブワ、オダワ、ポタワトミ、サック、ワイアンドット、レナペといった先住民族の間で締結された条約であり、これらの部族はすべて、1783年にアメリカ合衆国がイギリス王国から獲得したヨーロッパ人の領有権の範囲内で領有権を主張していた北西部領土に属していた。

フォート・ハーマー条約は、1789年1月9日に北西部領土のフォート・ハーマーで締結された。ハウデノソーニー、オジブワ、オダワ、ポタワトミ、サック、ワイアンドット、レナペの代表者である各民族の指導者たちが、北西部領土知事アーサー・セント・クレア、ジョサイア・ハーマー、リチャード・バトラーを含むアメリカ合衆国の条約交渉担当者と会談した。
この条約は、 1784年のフォート・スタンウィックス条約と1785年のフォート・マッキントッシュ条約という、それ以前の2つの条約の問題点に対処することを目的としていたが、実際には、わずかな変更を加えただけで、以前の条約の用語をほぼそのまま踏襲していた。この条約は、先住民諸民族の最も重要な不満、すなわち、先住民諸民族のために確保された領土にまで及ぶ西部保留地のファイアランズ地域への白人アメリカ人の無許可入植という問題に対処できなかった。
Arthur St. Clair was authorized by Congress to offer to exchange other land reserved for U.S. settlements for the disputed Firelands of the Western Reserve. St. Clair refused to give up these lands. Instead, St. Clair negotiated a treaty that simply reiterated the terms of previous treaties through means of bribery and threats. Many leaders of Indigenous nations met prior to the negotiations to determine an appropriate strategy. Joseph Brant, a Haudenosaunee leader, offered a compromise position which moved the boundary line to the Muskingum River.[1]:108–110 After other Indigenous leaders rejected this compromise, Brant sent St. Clair a letter asking for early concessions. St. Clair refused and accused Brant of acting for the Kingdom of Great Britain. Brant decided to boycott negotiations with the United States and suggested others do the same. Further deteriorating the situation was the murder of a Haudenosaunee leader named by Tegunteh by a White man named Lewis Wetzel.[2] Although Wetzel was twice arrested for the crime, U.S. authorities never punished him. Several nations, including the Shawnee and Miami, refused to participate as a result of St. Clair's belligerence, and therefore were not bound by the treaty.
The treaty failed to stop the violence in the region caused by the encroachment of White Americans onto territories held by Indigenous nations. Many nations were infuriated at the treaty because they perceived the treaty to force land cessions and foreign sovereignty over.[1]:113 The failure of the treaty led to an escalation of the hostilities as the Western Confederacy resisted the United States invasion. The war would continue for six years and see thousands killed, including some of the worst defeats in U.S. Army history, until the United States defeated the Indigenous alliance at the Battle of Fallen Timbers in 1794.
In the 1795 Treaty of Greenville, the nations were forced to give up 3/4 of their lands within what is now Ohio. This treaty divided the Northwest Territory into two parts — one for citizens of Indigenous nations and one for United States citizens.