The short answer is geography.
It was mainly because the wars started on European soil and there is an ocean between US and Europe. Japan started the war in China and some islands in the Pacific, and there is also an ocean between there and the continental US. Also, US is a very large place.
It was (and still is, to a large extent) very difficult to move an army large enough to invade such a big country across that great of a distance. You would have to transport not just soldiers and guns, but also cannons, tanks, trucks, ammunition, fuel, food, medical supplies, and many other things a fighting force needs. This would require a large fleet of ships, which would be noticed from afar, giving US time to prepare making the invasion's chances for success minimal. Germany and Japan probably didn't have enough ships and fuel to pull this off, anyway.
At the time of WWI and WWII there were no weapons with long enough range and enough power to do serious damage to another continent other than an invasion, at least until the atomic bomb, and US beat everyone to the punch with that. A submarine could come to American coast unnoticed, but the submarines at the time were small and could not carry any armament useful against land-based targets.
No battles fought here
their were no battles within the mainland.
In WWII, Alaska & Hawaii were US Territories; NOT STATES. The US Mainland was referred to, as "the states."
No.
Home Front
No battles fought here
World War II got the U.S. out of the Great Depression and there was no fighting in the U.S. so the government didn't have to pay for the damage that other countries had to pay for.
their were no battles within the mainland.
No rapid German retreat and Italian surrender helped spare the city
how many people suffer from anerexia iin the world
the benefit of disarming a weapons is that weapons like nukes have a pressure trigger that can be deactivated under certain circumstances which can only cause minimal damage if a disarmed nukes hits the ground, it will cause a small amount of environmental damage
There are many people in the world who suffer from ablutophobia. Many of these people go undiagnosed and do not get help.
A foothold In mainland Asia,got a modest amount of money (that was spent on projects that would someday involve pearl harbor) and minimal causualties...they STILL felt like they got the bad end of the deal.
Temporarily allied during World War II, the US and the USSR became competitors and the cold war resulted. World War II also through many nations into untold economic depressions.
Off the west coast of mainland Europe.
Reference point? I always preferred World Book Encyclopedia but I don't know if they still make them. Don't put them in front of your vehicle because they may suffer damage.
The US mainland is the 28 contiguous states of North American Continent. Alaska and Hawaii are considered not to be part of the mainland and the possessions too are not part of the mainland. However, the 50 states are solidly all part of the UNITED STATES. In World War 2 it was also know as the HOME FRONT.