Spain opened the lower Mississippi River to American Shipping

Answer 1

Depending on the time period in question, it could be argued that Spain did, in fact, provide the Americans access to the lower Mississippi river through the Port of New Orleans in 1795. This duty-free access stemmed from the Treaty of San Lorenzo/Madrid signed between the United States and Spain which certainly helped establish business/trade arrangements that were favorable to the United States. Spain held territory west of the Mississippi River at that time and controlled Florida and west to the Mississippi, which was about the lower 10% of the river.

Spain acquired this territory in 1763, as France singed a treaty with Spain giving Spain possession of the territory.

Answer 2

France did this, not spain