---
title: "Adams-Onís Treaty Definition | Model Diplomat"
description: "The Adams-Onís Treaty of 1819 ceded Florida to the U.S. and defined the Louisiana Purchase's western boundary, impacting U.S.-Spain relations."
url: "https://modeldiplomat.com/learn/glossary/adams-onis-treaty"
---

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Model Diplomat Research Team · Last reviewed June 22, 2026

TL;DR

- The Adams-Onís Treaty of 1819 was a U.
- S.
- Why was the Adams-Onís Treaty called the Transcontinental Treaty?
- What did the United States give up under the treaty?
- How did Andrew Jackson influence the treaty?

[Civil Service & Diplomatic Exams](https://modeldiplomat.com/learn/civil-services/glossary)Updated June 22, 2026

The Adams-Onís Treaty of 1819 was a U.S.-Spain agreement ceding Florida to the United States and fixing the western boundary of the Louisiana Purchase.

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## Timeline

1. 22 February 1819

   The Adams-Onís Treaty, signed on and formally titled the Treaty of Amity, Settlement, and Limits between the United States and Spain, was negotiated by Secr…

2. 22 February 1821

   Ratifications were exchanged on , two years after signing, owing to delays caused by Spanish concerns over American recognition of the rebelling Latin Americ…

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Example

In 1819, Secretary of State John Quincy Adams and Spanish minister Luis de Onís signed the treaty by which Spain ceded Florida and fixed the U.S. boundary to the Pacific at the 42nd parallel.

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