There are three major components to the debate of the impact that immigration has on the US economy. The first is the notion of immigrants displacing US citizens in the job market. To this issue there is also the related issue of immigrants lowering wages. As these two items are related I’ll tackle them together. The other notion is that immigrants take more benefits from social welfare programs then what they contribute thus negatively impacting US taxpayers.
First let us address the notion of wage and job displacement.
In regards to the discussion about immigrants taking more out of the social welfare system then they contribute we must separate the issue into two general components – federal social services and state and local services such as schools and other support expenses. However, first we need to clarify one of the largest misconceptions in the immigration debate – the difference between Mexican-Americans and citizens of Mexico. Generally and as used in the immigration debate the word Mexicans and Mexican-Americans do not differentiate between a US citizen born in the United States that is of Mexican descent and an immigrant from Mexico.
A US citizen, regardless of ethnic origin is a US citizen and for the purposes of the debate on welfare systems and the impact by immigrants on them has no place in the argument. A US citizen, regardless if they are of Mexican descent have the same rights to access social services as any other US citizen. Their use of welfare systems is an argument to be had on the merits of the welfare system and not on immigration issues. As discussed previously in the history section, those that ascribe to being Mexican descendents have been present in the United States prior to the formation of the US and thus have the right to define internal politics within the US as any other US citizen. This right includes the welfare systems.
As for job displacement, the agriculture and construction sectors of the economy have continuously stated that they need immigrants for work related activities. Seventy percent of the paid labor performed in US farms is delivered by immigrants.  The top five percent of US farms generate 74 percent of the agriculture produced in the country. They account for 80 percent of the total expenses related to farm labor.  In 2007, US farms spent about $22 billion on farm wages.  Famers argue that the domestic labor market is unable to fill the labor needs because the work is “more physically demanding and less well compensated than nonfarm jobs requiring similar skills.” 
The Immigration Reform and Control Act of 1986 recognized the need for immigrant agriculture laborers and authorized over 1.1 million farm workers.  The problem though is that the agriculture sector of the economy continues to grow and no additional provisions have been made for additional migrant labor to fill the need. At the same time, increased security at the border has forced Mexican laborers who previously remained in the US on a temporary basis for work to now remain the US in order to avoid the increased scrutiny.
The fact is that immigrant labor helps to keep domestic food prices affordable to the US consumer.