[TheCoelacanth]

27th amendment was about congressional salaries and had basically no effect on governance.

26th amendment lowered the voting age to 18 for state and local elections and had no effect on national elections (statute already set the national voting age as 18, but courts prevented it from applying to state and local elections).

25th clarified presidential succession to work exactly how everyone had already assumed it to work for over a century, so for practical purposes did nothing.

24th in 1964, which outlawed poll taxes as a criteria for voting, was the last amendment with any effect on national governance.