Illegal Immigration At Record Low

The number of apprehensions made by the Border Patrol declined for the third year in a row to 724,000 in 2008 after breaching a mid-decade peak of 1,189,000 in 2005 . . .
Border apprehensions in 2008 were at their lowest level since 1973.

From here.

Immigration to the United States from Mexico and Canada was largely unregulated until 1952.