We’ve been fortunate to visit Brazos Bend State Park in Texas a number of times over the years. Apart from the more exotic birds (from a European perspective) there appeared to be plenty of coots and moorhens, just as on most lakes in the UK.
However, the loquacious and overactive ‘moorhens’ did not appear to behave at all like those in UK. Yes this was usually the mating season around March, but surely these were not the same species. A web search shows that they are common gallinules, which were given a separate categorisation from moorhens only in 2011. Their mating behaviour is quite spectacular!