The realm of corporate control in which we see the most effects that can be clearly shown, is that of foreign affairs. USA corporations have a long and sordid history of creating foreign affairs policies, from Cuban Independence to the Mexican Revolution, to the Nicaraguan interventions. The most notorious of these corporate interests would probably have to be Sam "The Banana man" Zemurray. His company "United Fruit" essentially wrote the US foreign policy towards Latin America Single-handedly in the early to mid 20th century. Interventions all across central and southern America were fueled by his interests, most famously in Nicaragua, where Augusto Sandino would be labeled a 'bandit' similarly to how 'terrorist' is used today by the company and prompt utterly unnecessary levels of USA intervention. All of this type of intervention started after the Spanish-American war, when businessmen started realizing how profitable it could be to intervene in foreign nations.

In terms of within the US itself, I'm less knowledgeable, but I can name several famous examples of companies with powerful interests making laws that benefited them, from the campaign for the illegality of Marijuana, from the deregulation of the pharmaceutical industry in the 80s, and a number of other examples exist as well. The US, but not JUST the US, let's not kid ourselves, has a long history of companies shaping government policy.