[bobthepanda]

For the presidential ballot this is true.

For the local school board or mayor, this is less true, because nearly all third parties do not field separate candidates in these races. It’s possible to win these races since the margin of victory is measured in the hundreds or single-digit thousands, but none of the third parties build up a base and instead shoot for the moon and inevitably lose.

[dragonwriter]

> For the local school board or mayor, this is less true, because nearly all third parties do not field separate candidates in these races.

In mich of the country, school board (and in somewhat less, mayoral) elections are nonpartisan. Its true that some local races are poorly contested, but that's actually largely unrelated to party structure, and more related to an insufficiency of people interested in the job (this usually isn’t a problem for mayors and schoolboards.)

Where these races are partisan, minor parties frequently contest them, and even where they aren't, minor parties can be found organizing around them (though where they are formally nonpartisan, you may not notice this, since the endorsement of the third-party may only be actively highlighted to party members.)

> It’s possible to win these races since the margin of victory is measured in the hundreds or single-digit thousands

And third parties do win them. Virtually all of the third party elected officials in the US are exactly this kind of local official, with a smaller number of state officials.

[bobthepanda]

it's a very small number; there have been 117 Green Party office holders, ever, across the entire United States, even though there are more than half a million elected positions in the US. And most of those people were not initially elected as Greens.

There has basically been no successful attempt to set up an ongoing party infrastructure and base, that actually wins elections. Pretty much all independent politicians in the US are one man shows.