How Many Legal Immigrants Live in the USA?

In 2007 according to the U.S. Department of Homeland Security Office of Immigration Statistics 1,052,415 individuals gained legal permanent residency in the USA.

The Last Ten Years Among Highest Number of New Legal Permanent Residents
The tables provided by Homeland Security indicate, that the last ten years are among the three decades with the highest number of people who gained legal permanent residency since 1820 with a total of 9,359,479 people between (and including) 1998 and 2007. The same document shows that only the previous decade and the decade before World War I saw higher numbers with over ten million individuals gaining legal permanent residency in the USA.

By country:

• Bangladesh: 12,074 (the second highest number of Bangladeshis to become legal permanent residents in the last decade)
  
  
• Peru: 17,699 (the second highest number of Peruvians to become legal permanent residents in the last decade)
  
  
• Romania: 5,802 (the fifth highest number of Romanians to become legal permanent residents in the last decade)

Nonimmigrant Admissions
In 2006 a total of 693,805 students with an F1 visa entered the USA. This number has slightly increased over the past three years (2003: 617,556). In addition, the year 2006 saw a total of 33,667,328 nonimmigrants [with different types of visa] admitted to the USA, a number, which has roughly stayed the same during the previous nine years.

[I chose to look at the F1 visa type more closely because it is very common for graduate students. It usually allows students to work for the university and after a year outside of campus in addition to studying. There are many other visa types. Another common student visa is J1, which allows the student to study or do research work but only with special permission and in connection with the student's study field allows her/him to work on campus.]

By country:

• Bangladesh: 14,224 (a number that peaked at over 20,000 in 2000 and 2001 but has roughly stayed the same over the previous ten years, 1998: 14,173)
  
  
• Peru: 199,286 (which is roughly estimated slightly lower than the average of the previous ten years, 1998: 192,848
  
  
• Romania: 70,462 (the highest number in the previous ten years, steadily grown from 33,307 in 1998)

What Is the Difference Between Permanent Legal Residents and Nonimmigrants?
The 2006 Yearbook of Immigration defines naturalization and nonimmigrant admission on page seven: “Naturalizations refer to persons aged 18 and over who become citizens of the United States. Most legal permanent residents are eligible to apply for naturalization within five years after obtaining LPR [Legal Permanent Resident] status. […] Nonimmigrant admissions refer to arrivals of persons who are authorized to stay in the United States for a limited period of time. Most nonimmigrants enter the United States as tourists or business travelers, but some come to work, study, or engage in cultural exchange programs."