2. to allow more trade between countries
Yep, number 2 :D
Because after the second world war, there was a surge of immigration that flowed to the United Staes. There was also a substantial amount of people who were intelectuals that were flocking to this country. All of this led, of course, to dramatic changes following World War 2.
The difference is 100 years there were 6 units and today there are 3,200 units. I hope this helps you :]<span />
