Not that simple, Ptarmy, local governments are ultimately backstopped by their State when they default. Default by an actual State government, or the Feds, is totally uncharted territory and would be a chaotic situation, with the stock market's typical reaction to chaos as a result.
The debt ceiling issue would be a pretty technical default and if it actually happened, everyone is expecting the Congress would have to resolve it one way or another immediately after the first payment to bondholders was missed, with all the bondholders being made good pretty quickly, so it would not be anything but a nine-day wonder. Default of States like California or Illinois is a whole different thing, their ability to reconvene, reconsider, and do something ugly to slap a patch on the system is completely different and less-powerful than the Federal government's, and therefore a State default does have the potential to cause a cascading economic crisis...California in particular though seems Hell-bent on trying to explore 'What would happen if' on that one, though.