Final answer:
The nation's approach to policing citizenship boundaries has evolved over time, particularly with heightened enforcement post-9/11 and contentious legislative efforts like the Comprehensive Immigration Reform Act of 2006.
Step-by-step explanation:
The nation's approach to policing the boundaries of citizenship began to take shape significantly during the early to mid-20th century, with transformative laws and policies such as the 1986 Immigration Reform and Control Act. However, it was not until the post-9/11 era that this approach became characterized by a more stringent enforcement outlook, culminating in various legislative efforts and border security measures throughout the early 21st century. Policies since then have grappled with complex issues such as demographic changes, undocumented immigration, and debates over the legal pathway to citizenship.
One notable attempt at reform was the Comprehensive Immigration Reform Act of 2006, which, among other provisions, sought to elevate the role of English as a common unifying language. The legislature consistently faced challenges, evidenced by the failure to pass this act, reflecting the deep national divisions on immigration policy. Further, high-profile legal actions like Arizona v. United States highlighted the ongoing struggle between federal and state authorities regarding immigration control and enforcement.