A major difference between the Fourth Wave and early eras of immigration is the large group of illegal or undocumented immigrants among them. Many come over legally on temporary visas, but stay after the visas expire. Others walk in without visas, mostly over the Mexican border.Most illegal immigrants are desperately poor, unskilled workers who come to America to take the lowest-paying jobs in our economy( just like the Irish in the mid 1800s). They are the farm workers, construction workers, housekeepers, dishwashers, gardeners, and meat processors. As the number of illegal immigrants swelled to an estimated 5 million in 1986, a new Immigration Reform and Control Act (IRCA) was passed to deal with the problem.The IRCA attempted to halt the influx of new illegals, while granting amnesty to existing illegal immigrants who wanted a chance to become legal US residents. It imposed fines of up to $10,000 on employers for every illegal immigrant they employed.The IRCA succeeded in legalizing over two million immigrants but failed in its other goals. Due to easily available fake IDs and inadequate funding for the Immigration and Naturalization Service to inspect workplaces, the IRCA did not deter employers from hiring illegals, whom they could hire more cheaply than US citizens or legal immigrants. The number of illegal immigrants has skyrocketed in the last 20 years to an estimated 11 million people. In the 2000s, as in past eras, high US unemployment combined with a rising number of immigrants produced a nativist anti-immigrant backlash. Vigilante groups such as the “Minutemen” patrolled the southwestern border. Anti-immigrant legislation included a controversial Arizona law requiring police to check people’s immigration status. Despite widespread agreement that immigration laws needed updating, a bipartisan effort to pass reform under President Bush collapsed in 2007. Instead, the Republican-led Congress opted to increase border security, constructing a multibillion-dollar fence on the Mexican border and doubling the size of the border patrol. They also vastly increased the number of immigration agents. As a result the Bush and Obama administrations vastly increased deportations and cracked down on employers who hire illegal immigrants. This crackdown on illegal immigrants, combined with demographic changes in Mexico, and the downturn in the US economy since 2008 have contributed to a drop in illegal border-crossings from an estimated 600,000 per year in 2005 to a mere 85,000 by 2011. But the crackdown also brought new problems— dividing families, depriving businesses of employees for low-paying jobs — without ending the problem of having an estimated 11 million illegal immigrants already living in the US.