The Guardian newspaper has published a special photography feature documenting a Pig Save event in Los Angeles.
A photographer went to the event to record the activists paying witness to the animals on their way to slaughter.
The mainstream media coverage of the event suggests the 'Save' movement is gathering pace.
The feature says that around 100 vegans attend the vigil every Sunday.
It adds: "No one witnesses their protest aside from the Vernon police department, which shows up to oversee proceedings."
The report notes the emotional impact the vigils have on the attendees, saying the activists 'frequently find proximity to the animals shortly before their deaths overwhelming and upsetting'.
According to the report: "Activists use flashlights, iPhones and headlamps to shine light into the depths of the truck without startling the animals.
"Los Angeles Animal Save encourages all participants to document the condition of the animals and either live-stream or post their pictures and video on social media in order to encourage more people to embrace a vegan lifestyle."
It notes how the activists give water to the thirsty animals - who reportedly will not have been given food or water during their journey to the slaughterhouse, which may have taken several days.