Six months ago from Wednesday, the Deepwater Horizon oil rig exploded in the Gulf of Mexico, killing 11 workers and causing the largest oil spill in U.S. history. Experts say it could be years before we fully understand the impact of the spill. But before the Deepwater Horizon, it was an oil spill in Alaska's Prince William Sound that held that title. Twenty-one years ago, the people in that community endured an experience that is similar in many ways. From the mountains to the marshes, they are two very different communities more than 4,000 miles apart. Valdez, Alaska is home to rocky beaches, sea otters and salmon. "We always considered Prince William Sound our bread and butter," Alaska fisherman Mark King said. Venice, Louisiana is where shrimp and crabs are the catch, pelicans nest and wetlands carve the coastline. Most in both communities have a connection either to oil or fishing. And in some cases, both. Like Dave Totemoff from the native village of Tatitlek, Alaska, fishing and hunting are the backbone of the community. "It's still sad," he said. Totemoff also works in oil on the North Slope before it travels 800 miles through the Alaska pipeline to Valdez. "Before the oil got to Valdez, I was working on the same oil in Prudhoe Bay," he said. "I couldn't go back for two years because there was so much personal feelings I had." In Prince William Sound, it's tankers that move oil from the Valdez terminal. In the Gulf, more than 3,000 platforms extract oil in both shallow and deep water. The people in both places understand the aftermath of an oil spill. In the early morning hours of March 24, 1989, the captain of the Exxon Valdez had to navigate around ice and struck a reef. During a foggy afternoon on Prince William Sound, it's difficult to see the markers, but it's where the Exxon Valdez ran aground about 30 minutes after it left the terminal. The bottom was ripped from the vessel, and 11 million gallons of heavy crude were released. Few pieces of equipment were ready to respond to the spill. There was little or no containment boom in the area. "It kind of just started slowly, just changing our whole community," King said. Two days later, a massive storm blew into the Sound. Within two months, the spill stretched 460 miles to the Alaska Peninsula, damaging 1,300 miles of coastline. Marine mammals died, fish were killed and the village of Cordova was left stunned. "Recovery is a very complex thing, and it takes a long time," Alaska fisherwoman Torie Baker said. Twenty-one years later, an explosion on the Deepwater Horizon drilling rig killed 11 workers and injured 17 more. Two days later, the rig sank and light crude oil from the operation was leaking into the Gulf. "You could smell it," said Joe Vosicky, a Gulf coast resident. "It was like a hot crayon." In the weeks following, birds were found dead; other oiled animals were rescued. "You look at all the animals and the birds that the oil was affecting, and we thought it was so close to home," Gulf coast resident Ronald Bell said. Tar balls were found from Florida to Texas. "Selfishly, you don't want it to come to your own community," Gulf coast resident Kim Vosicky said. Oil washed into the marshes of Louisiana and beaches in Alabama and Mississippi. Dispersants were dumped into the ocean to break up the oil while crews worked to cap the well and drill a relief well. The well was capped on July 15. A final kill was in place almost five months after the accident, but not before the Deepwater Horizon had become the world's largest offshore oil spill. In the end, it's believed almost 200 million gallons gushed into the Gulf, more than 10 times that of Exxon Valdez.