For New Hampshire, they did have two Republicans representing only about ten years ago. See for yourself here -

https://en.wikipedia.org/wiki/New_Hampshire%27s_congressiona...

Now, considering their redistricting happened in 2010 and 2022, perhaps their voters simply felt it appropriate to change. But what could’ve occurred in 2016 to convince people that Republicans suck? Maybe electing a guy that wants to figuratively fuck working class Americans and literally fuck his own daughter left a bad taste in their mouth.