Federal funding for scientific research didn't exist 100 years ago; instead, it was supported through charities and wealthy philanthropists. Now, major federal agencies like the National Science Foundation (NSF) and the National Institute of Health (NIH) play a significant role in scientific research in the United States. For example, the NSF currently funds around 20 percent of basic research in academia, and nearly all research in fields like math and computer science. While federal organizations have played an important role in the production of scientific knowledge, the downside is that the government has a say in which projects get funding, and personal beliefs and politics can hinder scientific progress. Depending on who is in office, this can have deeply negative effects for specific fields, as when George W. Bush cut off federal funding for stem cell research in 2001.
(Pictured: a colony of human embryonic stem cells.)