From the Summary: "When President George W. Bush announced his principles for immigration reform in January 2004, he included an increase in permanent immigration as a key component. President Bush has stated that immigration reform is a top priority of his second term and has prompted a lively debate on the issue. Thus far in the 110th Congress, a variety of bills (H.R. 75, H.R. 938, H.R. 1645, S. 1038/H.R. 1930, S. 1348, and S. 1639) would revise categories for permanent admissions. A bipartisan compromise proposal for comprehensive immigration reform was introduced in the Senate on May 21, 2007, as S.Amdt. 1150 to S. 1348, the Comprehensive Immigration Reform Act of 2007. A modified version of that compromise (S. 1639) stalled on the Senate floor at the end of June 2007. Hearings have been held in the House on H.R. 1645, the Security Through Regularized Immigration and a Vibrant Economy Act of 2007, or STRIVE [Security Through Regularized Immigration and a Vibrant Economy]. […] Four major principles underlie current U.S. policy on permanent immigration: the reunification of families, the admission of immigrants with needed skills, the protection of refugees, and the diversity of admissions by country of origin. These principles are embodied in the Immigration and Nationality Act (INA). [...] The INA specifies a complex set of numerical limits and preference categories that give priorities for permanent immigration reflecting these principles. Legal permanent residents (LPRs) refer to foreign nationals who live permanently in the United States. During FY2006, a total of 1,266,264 aliens became LPRs in the United States. Of this total, 63.4% entered on the basis of family ties."
CRS Report for Congress, RL32235