Let's start with the prisons about to be built, of which there are still many. A campaign to convince the Travis County (Austin) commissioners not to fund a new $80M women's prison succeeded this week. Next step is to get them to instead fund diversion and mental health programs.

You may find similar movements that you can join in pressuring local officials. The fun thing is that at this level of government, commissioners will often respond themselves, so you know even relatively few emails are making an impact.