the 3 mile limit is the name of the boundary that separates the territorial waters of most coastal states & territories from the federal territorial seas that enclose them
but in the cases of Texas & Puerto Rico & the gulf coast of Florida it is called the 3 league limit or 9 mile limit
the equator...... i think
8891 kms
It's there to show that your crossing into a different country's territory.
water
The Atlantic Ocean.
The Northern Atlantic
That would be the Rio Grande river.
Lake Erie
No body of water separates the US. from Mexico
black sea
black sea
The river that separates the east and west U.S. is usually considered the Mississippi.