h1-b chart

In a presidential election season riddled with anti-immigration rhetoric, two recent studies highlight the importance of high-skilled worker visas to the tech sector.

Five of the top six companies receiving the highest number of high-skilled worker visas, known as H-1B visas, were tech-related firms in 2015, according to the National Foundation for American Policy, a non-profit policy research organization, citing data from the U.S. Citizenship and Immigration Services. Tech giants like Amazon, Microsoft, Google, Intel, Apple, Oracle, Facebook and Cisco fell within the top 30 companies that received the most H-1B visas as well. A total of 26,000 employers hired at least one employee through the H-1B program last year, the study said.

The tech community has long called for an increase in the number of H-1B visas given out each year, which has been capped at 65,000 since 1990. They argue this limit was set before the boom of the internet created a shortage of U.S. graduates in science, technology, engineering and mathematics, also known as STEM. By 2018, the United States will face a shortfall of more than 223,000 workers in STEM fields, according to a 2015 report by the U.S. Chamber of Commerce and immigration reform groups.

Silicon Valley’s reliance on H-1B’s has been criticized by Republican presidential candidate Donald Trump and others, who cite instances where companies have underpaid foreign workers as an alternative to hiring U.S. workers who aren’t reliant on a visa sponsor and demand higher pay. Yet H-1B workers “generally earn the same or more than their U.S. counterparts,” according to data from the Government Accountability Office. Workers under 30 years of age in programming and other computer-related occupations earned a higher median salary, the foundation study reported.

A tech agenda released by Democratic presidential candidate Hillary Clinton in June said she would “staple” a green card to STEM master’s degrees and PhDs from accredited institutions, to allow more high-skilled immigration.