In the Earlly 1800's America had grown to a great extent. And now the nation was coming into conflict with the European nations on our continent. Spain was showing signs of wanting to retake colonies they had lost. And in 1821 Russia claimed possession of lands as far South as Oregon.
In this climate, in 1823, President James Monroe declared that the American continents were no longer open to colonization. And He specifically asked/warned Europe to stay out of the affairs of Latin America.