It seems to me that America is a Melting Pot, and will benefit from the energy of new people. Always.
Your problem, is with our state giving out welfare, which I am against.
-John
There are a lot of problems, not just giving out welfare.
Your premise is ridiculous. America will benefit from new people, but not to the same extent as any other point in history as chosen. If that were the case, you would have no problem saying that every poor person in the world could immigrate to the US and our country would improve. There must be limits and standards. Every nation in the world recognizes this and implements controls to ensure that it is enforced. The US is among the worst in this regard.
A nation does not have infinite resources to support any number of immigrants while still maintaining the standard of living that its current citizens demand. I'm sure that it could be generally quantified how many immigrants we can support per year based on the economy, whereby significantly more would be detrimental.
The quote you posted is representative of an ideal of the time, when America was the refuge of those seeking escape from the repressive governments of the world, to live a life where they succeeded or failed based on their own merits and efforts. These days, too many take it to mean that America will provide for anyone and everyone who comes here looking for a better life.
America was not designed to provide for you, it was designed to allow you to provide for yourself without getting in the way.