American wine has been produced for over 300 years. Today, wine production is undertaken in all fifty states, with California producing 89 percent of all US wine. The United States is the fourth-largest wine producing country in the world after France, Italy, and Spain.

Based on this passage, where is the most wine produced in the us? Let's give stream of consciousness first:
The relevant sentence in the passage is: Today, wine production is undertaken in all fifty states, with California producing 89 percent of all US wine.
So, the final answer is California.