Your description of America growing to a world power from early “open” boarder policies lacks context. 

Pre revolution there was oftentimes extreme expense and hardship involved with immigrating to the USA, which often lead to indentured servitude to those whom paid for others way, slavery, or privately funded colonies bringing in people to farm and work the land- ie due to need.

There was actually very little immigration for the first 50+ years of the country’s history. Remember, it was VERY difficult to cross the ocean when this country was founded. Much more difficult to move around the world then compared to even the poorest of today’s migrants. 

In the mid 1800s, a large influx of citizens were naturalized due to the Mexican American war, and the California gold rush. But at this point still greater than 90% of the citizenry was native born, as a majority of pre revolutionary immigrant citizens had passed.

Post-1850 manifest destiny and the expansion of the country westward demanded an increase in population to settle the American west, which began the major wave of immigration we all typically think of when we think of immigration history. But it really wasn’t even until 1880 with steam powered ships that immigration really began to grow quickly.

Your comment regarding 1921 is simply false. Immigration law began post civil war in 1875 when the Supreme Court deemed immigration federal jurisdiction, which lead to the Asian exclusion act being passed that same year.