Families and survivors of gun violence marched across New York City's Brooklyn Bridge to demand tighter firearms laws.
Gun deaths in Virginia will be 31 percent higher than road traffic deaths by 2019.
Parker's daughter was fatally shot, alongside a colleague, on live TV two months ago in Virginia.
Alison Parker and Adam Ward were fatally shot on live TV in Virginia on August 26.
The medical examiner's office confirms the deaths were homicides.
Gardner was the third victim in a live TV shooting that left two journalists dead.
Andy Parker said he will do "whatever it takes" to shame lawmakers into passing tighter gun laws.
The two journalists fatally shot on Wednesday were remembered by their co-workers for brightening up a room.