Was headed from Snowflake to Phoenix coming back from a wedding. It's a bunch of mountains/cliffs you weave through at a really high elevation. Sign for curve gave a speed limit around the curve. It didn't look bad. I was probably doing 20 over (this number could be inaccurate). Thought I was in control. The curve ended up being much sharper and quicker than it look and there was dirt and gravel on the road. The car slid sideways across the gravel, into the other lane and then into the shoulder almost hitting that small little railing (huge cliff). Had there been a car coming the other way, I would have hit them. Had I been going any faster, we would have gone off that cliff. My older sister was in the car asleep. She had no idea why happened. For years, just thinking about that would give me chills because it seemed so real we could have easily died, but in reality nothing at all happened.