It's the U.S.-Mexican border.
country border? most likely now mexico.
the Mexican-American War
most likely just another state but especially if it is not called an international border
During World War II itself, German troops crossed the borders into numerous countries, both in Western Europe and in Eastern Europe (not to overlook their North African campaign). Perhaps the most significant border-crossings occurred in September of 1939, when the war began after Germany violated the Polish border, and in June of 1941, when Germany crossed the border of their "ally," the Soviet Union, and thereby ensured their ultimate defeat in the war.
During World War II itself, German troops crossed the borders into numerous countries, both in Western Europe and in Eastern Europe (not to overlook their North African campaign). Perhaps the most significant border-crossings occurred in September of 1939, when the war began after Germany violated the Polish border, and in June of 1941, when Germany crossed the border of their "ally," the Soviet Union, and thereby ensured their ultimate defeat in the war.
It is called the border. There are border crossing set up on most of them to control who comes in or out of the country.
It is not made of anything for the most part. At one time there would have been a lot of checkpoints, though there are very few now. So apart from where you might cross a bridge over something like a river, as you drive along the road and cross the border there is nothing there at that point to indicate that you have crossed it. After you've crossed it you will notice things like the road signs being in a different style and they are often the first indications that you have crossed the border.
Mexico!!!! There is a common international border between the two nations.
Yes, although most made it out with the government's permission, which is enforced. Some crossed the border without permission safely though.
The mountains on the northern border of Italy are known as the Alps. They make a natural boundary between Switzerland and Italy.
Carried out by international non-governmental groups Al-Qaeda is the most famous example
more frequently, most frequently