You can help foster this mentality through community action groups. Highly focused groups at first but with ever expanding reach.

For example, your street is full of potholes and the city refuses to prioritize their repair. Organize a group, which will likely include folk across the political spectrum, to take on the task. Maybe one person has the tools, a few other can provide the man power and others can put on a bake sale for the bags of ready asphalt, etc. Next thing you know, no more pot holes. Maybe that expands to the entire neighborhood, then maybe you take on trimming dangerous tree branches, etc, etc. This type of action tends to help people who participate in the activity to expand their sense of ownership and become protective of things beyond what they purchased. It hopefully goes from limited to their house, to their street, to their neighborhood, city, state, etc. Along the way you can also expand the scope of care beyond material things with the same techniques.

I used to live in Austin, a famously progressive city. Nobody helped anybody else. I have also lived in southern Louisiana and now live in the Jackson Hole Wyoming area. Neither location is what you'd call a hotbed of progressive thought. In Louisiana, I was dirt poor and everyone helped everyone by default. When everyone is down in the pit of hell and the rest of the world doesn't even acknowledge your existence, you help where you can because why the hell not.

In the Wyoming/Idaho border you find billionaires (very small minority) and people holding multiple jobs (vast majority). The billionaires want to keep their little slice of heaven "suburbanite free" and want to make sure that their quality of life doesn't degrade, so they tend to give a lot to the community (a lot is relative. loose change to them). The rest, help each other out, especially in winter. Trails are volunteer maintained. Food banks, clothes and gear is donated and freely available. If you are snowed in, a cry for help on Facebook will get you sorted in no time..etc.

Don't underestimate the power of feeling a sense of community.