How would you grade America’s first 250 years? That’s the question I posed to historian and professor Heather Cox Richardson on this week’s episode of America, Actually — and a question I pose to myself. All grades are subjective, and the rubric of whether America earns a passing grade is one of position and perspective, but the best I could come up with was a B-/C+. The enduring model of multiracial democracy, however fragile it currently is, deserves some credit. So does the long list of American inventions and academic institutions, and the cultural impact of American music, film, and sports. With some demerits for the permanent underclass capitalism requires, injustices here and abroad, and preferring the wrong type of football, a passing grade seemed fair enough. In our interview, Richardson said that she sees the country as entering a period of enormous change, particularly as President Donald Trump continues to reshape our government to serve his maximalist desires.…