Around 300,000 people cross the northern border with Canada each day, which equates to annual approximates of 39,254,000 crossings by Canadians into the United States (in 2009) and 20,213,500 crossings by Americans into Canada (in 2010). The southern border with Mexico was crossed by more than 20 million Americans in 2013 and over 14 million Mexican tourists coming the other way.
It is difficult to tabulate the exact figures on border crossings, since a number of Illegal border crossings are successful and therefore unrecorded. The number of apprehensions of illegal immigrants crossing the southern border from Mexico was at its lowest since 1972 (321,326) in 2011, when there were a total of 327,577.
This is likely attributed to fewer Mexicans wanting to enter the United States illegally, which in turn is perhaps due to the deterrent of an increased presence of U.S. Border Patrol agents — especially in the southwest.
Meanwhile, crossings from the south by Mexican citizens directly benefits the U.S. economy. Tourism from south of the border brought $10.5 billion into the economy during 2013, for instance.
Given all of the possibilities of border crossing, it is difficult to pinpoint exactly how many people cross the US border yearly but it can be estimated to be upward towards a hundred million.