Thursday marks 20 years since a 28-year-old man went on a shooting spree in Tasmania, killing 35 people and wounding 28. It was the worst massacre Australia had ever seen.
The gunman, Martin Bryant, now 48 and imprisoned for life, was later assessed to have the IQ of an 11-year-old. He told investigators that he'd paid cash for firearms at a local gun dealer.
Australia had experienced mass shootings before, but the Port Arthur massacre prompted the government to introduce legislation that outlawed automatic and semi-automatic rifles, as well as pump-action shotguns. A nationwide gun buyback program saw more than 640,000 weapons turned in to authorities.
In Australia, a single massacre changed everything. But in the United States, the question is often asked in the somber aftermath of a shooting massacre: how many deaths will it take before America changes its gun laws?