Is this true?

I haven't looked at any data, but I'd assume any areas with higher proportions of white people will have a taller average height. White people are the tallest. Black people might be about as tall as white people on average in the US, but everyone else is shorter.

dutch areas of the US are a fair bit taller than normal in my experience

I'm from a very dutch part of michigan and I stg it's like all the dudes here are 6'+

Yes of course. Stronger gravitational pull from the moon due to the tilt of the earth. Common knowledge

5’9.5 is the average for a white, 5’9 for a black, 5’6 for a Hispanic, and apparently 5’7 for an Asian. However I seriously doubt these statistics, they are probably self reported heights mostly. Because I was just at the Niagara Falls were there is a melting pot of races from all over the world there, and most of the tourists were Asian, Indian, brown Hispanics and Arabs, and I was taller than most of them and not just by a little bit. I’m a 5’7 and some change and was wearing a boot with a little over an inch heel. So basically 5’9 with boots on. Granted these are tourists and not Asian Americans, Indian Americans, etc But still these people are absolutely tiny. I was seeing lots of guys under 5’5, some even 5’2 range.

Not clear why this matters. Height is an advantage in most career competition. Not worth too much neuroticism about.