We tend to think of an unfree press as being subject to political / governmental pressures.
In the US, it is the "free market" economy that creates the infringement on freedom of the press.
"If you run that story, my company will pull all our advertising from your paper, and from every one of your sister papers across the country".
Anything deemed 'Anti-American' - (such as reporting on the coffins of US soldiers returning from Iraq) - can provoke the anger of someone or other - and through organised campaigns, put pressure on the item to be dropped.
It happens across all types of media - there are well documented cases of television programmes being dropped from networks because of orchestrated campaigns by (for example) the religious Mid-West.
They don't bother with indignant letters to the television company, they go straight to the big advertisers (the Kellog's, Wal-Marts and Coca-Colas of this world) and say - "If you advertise during (*this programme*), we will boycott your product."
Net result? The advertisers fear isolating a large, organised section of their market. They express their concerns to the TV network / newspaper / Media Group, who worry about the loss of advertising revenue from their major 'sponsors' and - hey presto! - anything remotely contraversial is dropped.
Freedom US style.
(And, no this is not US-bashing - I haven't even started about what goes on here in the UK!!)