Florida's history during the late 1800s was most affected by U. S. foreign relations with which country?

Florida's history was most affected by U.S. foreign relations with the country

called  Spain.

Florida was formerly under the Spanish territory until the late 1800s when  

East and West Florida was given to the United States. The major difficulty

Spain had was not having enough resources in sending people and troops to settle in the region.

Some parts of Florida was given to the United States in exchange with

settling the boundary dispute along the Sabine River in Spanish Texas which

was done. This occurrences affected and changed Florida history.

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