I am asked frequently why people who immigrate illegally don't just come here legally.  That's a good question, and it deserves a good answer.Estimates from the U.S. Department of Homeland Security, the Pew Hispanic Research Center and USCIS show that 59% of all illegal immigration consists of people from Mexico.  Yet State Department Statistics show that only 15.6% of Mexican citizens who apply for business and tourist visas are refused.  Citizens of France, a more developed country in comparison, have an even higher rate of denial at 18.8%.  So what gives?French citizens are allowed visa free travel, unless they are ineligible for the visa waiver program for some reason such as criminal convictions.  That's why the only people who apply for visitor visas from France, for example, usually have some kind of special issue that needs reviewing.  Mexican citizens, on the other hand, do not enjoy visa free travel, and are required to obtain a visa first from the State Department before coming even for a day trip to go sightseeing.  Visitor status (technically, the B-1/B-2 visa valid for business (B-1) or tourism (B-2)) does not permit work.  It allows meetings, attending conventions, and going to Disneyland, but not working there.  Obtaining a visitor visa also requires the person to rebut the presumption of immigrant intent (see INA 214(b)).  Yes, the United States presumes every visitor to be an immigrant unless the person can show that they are not intending to immigrate (stay here permanently), and since a visitor status is inherently a nonimmigrant classification, the two don't mix.  If you can't overcome the presumption, you are denied.  In other words, don't bother applying if you're poor and don't have any assets.Because visitor status does not permit work, and because even obtaining a visitor visa requires the person show they are not likely to immigrate to the country, the people who apply for visitor status from developing countries more likely to be wealthy business people with extensive property holdings, and thus have the ability to show they are not likely to immigrate.A comprehensive treatment of the visa categories which allow work in the United States, or allow a person to immigrate to the U.S., is impossible in a short blog post such as this.  But suffice it to say that the United States does not have very generous work authorization schemes on the books.  The U.S. caps professional workers (for jobs requiring a bachelor's degree in a specific field) at 85,000 nationwide per year, and just received 233,000 applications for those limited numbers in a 5 day filing window April 2015.  The only real visa for non-professional work is the H-2B program, capped at 66,000 per year, which is designed for seasonal, peak load, one time occurrence, or intermittent work.  It is used by some summer agricultural employers, and some winter ski resorts. Employers must engage in a complex recruitment effort to make sure U.S. workers have a chance to apply first.  Annual quota number and limitations on the program itself make it unusable for most employers.  If you want to immigrate to the U.S., as opposed to just coming here temporarily, you need employer sponsorship or family sponsorship.  Most categories (with the exception of positions requiring a master's degree or a bachelor's degree plus 5 years of progressive experience) take many, many years to result in permanent resident status (the green card).  Even with a parent who is a U.S. citizen, an adult child of a U.S. citizen from Mexico will wait 20 or 30 years or more to immigrate, as the State Department is processing those with filing dates from the mid 90's and they inch the dates forward a few weeks every month, doubling the waiting time.The fact is, we have a 1980's style immigration system that was founded in 1952 at the height of McCarthyism, and last updated