Want more evidence there are really two Americas, politically speaking? The nonpartisan political tech startup, Crowdpac, attempted to rank every city (with a population over 6,000) by looking at which federal and state candidates their city residents have donated to since 1980. (Over 100 million donations in total.)

What Crowpac found probably won't surprise you; people in cities tend to be more liberal than people in rural areas, and the United States is increasingly divided into two — the liberal coast and the more conservative South and Midwest/Mountain West. According to its rankings, here are the 10 most conservative and most liberal communities in the United States. (You can check your town's ranking here.)

There are some familiar places there, particularly on the left; nobody will be surprised to see Ithaca, N.Y., or Berkeley, Calif., on that list. But despite the fact that many of the other city names aren't familiar, where they come from is quite familiar — lots of New York and West Coast on the "liberal" side and lots of the South on the "conservative" side.

Analyzing political donations is, of course, one way among many to analyze the true politics of a locale — but it's a particularly interesting one. Unlike voter registration data, which tells you which party people might belong to, political donation data reveals which candidates people are actively supporting. That helps paint communities in different shades of red or blue.

"We know San Francisco leans Democratic," said Mason Harrison, the political director for Crowdpac. "We don't know whether those Democrats are Dennis Kucinich Democrats or Joe Biden Democrats or Hillary Clinton Democrats."

In coming up with the rankings, Crowdpac analysts gave more ideological points to a city if donors there gave to candidates who sit closer to the ends of either side of the ideological scale. So if a city gave more to the more-liberal Bernie Sanders than to Hillary Clinton, that city scored more liberal than a Clinton-backing city would. (Crowdpac ranked candidates' ideology going back to 1980!)

This exercise is necessarily difficult, since some candidates don't fit neatly on the ideological spectrum; Donald Trump's positions on some issues are way out to the right, but he's not a down-the-line conservative, and he's actually considered one of the more moderate Republicans by Crowdpac. Some will certainly take issue with that characterization — along with Rand Paul being the most conservative Republican — but the rest seem to be about right. (Crowdpac also made sure to rank cities that had at least 10 individual donors, so as to not let one or two politically inclined millionaires skew a community's ratings.)

We'd argue another bonus of analyzing cities' ideologies by political donations is that you're catching the most politically active segment of the population. Donors are more likely to shape the political leadership of the community, which in turn is more likely to shape the community itself — and, possibly, who lives there.

And that's the biggest takeaway from this database: We are living in two countries within a country. That was driven home at the federal level recently by this map from the Federal Elections Commission showing which party controls a majority of each state's House delegations.

According to Crowdpac, that segregation holds up for the communities we live in, too. What's more, Harrison noticed that suburbs around cities tend to reflect the ideology of the city. The entire San Francisco Bay Area is pretty liberal, for example.

It's a bit of a chicken and egg situation about how our communities became so politically homogeneous. A 2014 Pew Research Center survey found what Americans value about their community tends to also divide them politically. About 75 percent of conservatives want to live where “the houses are larger and farther apart, but schools, stores and restaurants are several miles away," while 77 percent of liberals want almost the exact opposite, preferring smaller houses closer to amenities.

That in turn could be a self-fulfilling prophecy about where people chose to live: It's perhaps human nature to want to live among people like you, in communities and political systems that reflect your values.

Whatever the reason, this Crowdpac database is the latest example of just how polarized the United States is — right down to our neighborhoods.