For one, the social welfare atmosphere DID NOT exist. Did you get that? It DID NOT exist. Thus, the motive to immigrate here, was left mostly to those who could sink or swim on their own. Hence, it meant that mainly people who wanted to be Americans came. That, and the fact that you had to get on a boat to come to America. That big ocean had a positive effect in getting immigrants who felt loyalty to this country.
On the other hands, illegals just hop over the border. Furthermore, they've got special interest groups at their hands to sue the American public if they're "discriminated" against. Furthermore, if they can't make it on their own, they've got the taxpayers to support them through all types of social welfare. Not only that, they don't have to worry about learning English, for everyone they work for, due to declining wages, speaks Spanish, as well as mostly everyone they live around. Furthermore, you have a president who caters to them, and who addresses the nation in Spanish. You have Spanish television and radio, and you have a movement to turn the southwest over to Mexico. Furthermore, this movement, known for Aztlan, is much more known in Mexico than it is in the United States. Most Americans are ignorant of this.
Thus, given the above examples, along with the fact that past immigrants came from countries that had much more in common with the current American stock than does today's Mexico, it is obvious that there is a huge difference.
How could you deny such a thing?
Uh anti-immigration people were saying the same rhetoric as you are saying now. That's a fact.
Oh BTW, most people come to this country to find a better life for themselves and their families and that hasn't changed since America's inception and is still true today.