Agriculture is a prime area where mostly Mexican immigrants have put down roots so strong that companies may no longer be able to operate without them.

Here are some facts about US agriculture and immigration:

  • World Perspectives, an agricultural consulting firm, estimated that 40% of all immigrants in the US work in agriculture, and that 25% to 75% of US farm labourers are "fraudulently documented"

  • A recent study by the American Farm Bureau Federation said a crackdown on illegal immigrant labour could cause production losses in US agriculture of $5 billion to $9 billion in the first one to three years and up to $12 billion over four or more years

  • The Farm Bureau says despite heavy use of machinery to plant and harvest the largest US crops - corn, soybeans and wheat - Midwestern farmers often rely on cheap immigrant labour to do work that family members once did.