Many Americans are perplexed when they hear about immigrants coming to the country illegally. Why, they wonder, don't they simply apply for residency and get in the legitimate way — just like so many of their ancestors did 100 years ago? As we said earlier, the vast majority of immigrants do enter legally, but it's an arduous process today.
During the United States' first 100 years as a newly minted country, any able-bodied immigrant was allowed in. They just had to physically get here (though that was often problematic). Today, there are many rules about who can and cannot enter the country.
Most immigrants enter by obtaining a family-sponsored or employer-sponsored visa. These visas can be pricy ($200 to more than $700). The U.S. also limits the number of immigrants per category and by country of origin. On Nov. 1, 2014, there were 4.3 million people waiting for a family-sponsored visa, but just 226,000 family-sponsored visas were due to be handed out in 2015. (Visas for spouses and children under 21 aren't subject to limits.) Also, the number of immigrant visas handed out to citizens of any one country can't exceed 7 percent of the total number of visas each year. This means years-long waits for most foreigners. Some citizens of Mexico and the Philippines have been on the family-sponsored visa waiting list for more than 20 years [sources: Santana, U.S. Department of State].
If someone was trying to escape violence in his or her own country, or to reunite with family members, they may reluctantly opt for an illegal entry rather than waiting for years or decades.