There's no US state where the entire population shares a hive mind, so it wouldn't be possible to find any state where the majority sees things in exactly the same way. Of course, there are certain states where on average, people are more conservative or more liberal in their thinking, but there's no state that would qualify as being the "most" open minded because open mindedness and narrow mindedness do not remain consistent within the borders of any one state.
There are about 40 million people in California. There are fewer than 600,000 in the state of Wyoming. Most people would consider California to be a very liberal state primarily populated by open minded people, and most would consider Wyoming to be a very conservative state that's primarily populated by people who would likely label themselves as being more conservative. But the fact is that there are far more conservatives in California than there are in Wyoming. In fact, California is one of the most sharply divided states when it comes to the position the population takes on various issues. There are many communities in Northern California where the people tend to be very conservative, and there are pockets of conservatives all over the state. And not every single resident of Wyoming would profess to be a conservative, there are more liberal open minded people living in every state, so you'd face the same issue trying to arrive at a definitive answer as you go through each state one by one, process of elimination style.
New York? You must be joking. Upstate New York is full of people who would make people from the Appalachians and the Deep South blush in shame.
Florida? Pennsylvania? Washington? Oregon? They're all home to plenty of people who fly the conservative flag. Northern Florida is Dixieland. Most of Pennsylvania is quite similar to the surrounding parts of NY, Ohio, West Virginia and Maryland, all states with sizable conservative populations.
New England? The six states of New England are often touted as being some of the most liberal parts of the country, but there are plenty of people in Maine and New Hampshire who don't have a liberal bone in their body. Massachusetts has a reputation for being liberal, but Boston is frequently rated the most intolerant city in the nation. Vermont is home to some very open minded people, but there are a lot of people who are descended from people who have been there for generations who don't support liberal ideas - they're lumberjacks and blue collar people who are more traditional. Rhode Island has its share of white trash. Connecticut too.
Take a state like Missouri. There are a lot of blacks. It's home to a couple of very populous metro areas - St. Louis and Kansas City. But there are vast swathes of red all over the place in Missouri.
And this is not really a black and white issue, nor do things become easier just because there happen to be a lot of Latinos there either. Blacks tend to vote democrat, but that doesn't make them open minded. And many Latinos are just as religious as these Bible-beating evangelists who are always warning everybody they're going to Hell.
Even if there were some way of determining which US state was home to the most progressive thinkers, or which US state had the highest number per capita, what difference would it make? If you wandered out of the area filled with free thinking open minded people and entered an area where people didn't see things that way, it wouldn't matter which state you were in. And people don't live in pockets. They live right next door to one another, regardless of their convictions.
I suppose if I really didn't have a choice, people tend to be more open minded in places where they're generally better educated. I'd likely say that Massachusetts is statistically the most open minded state in the east and that Oregon was the most open minded state in the west, and while there are pockets of that sort of progressive attitude everywhere - in Colorado, etc., I'd say that there's a reason that type of approach is largely confined to the coasts.