California is, without question, the heart and soul of the Democratic Party. It's one of the most diverse and increasingly diversifying states; has a large liberal, college educated White population; its economy is dominated by industries and sectors that favor higher education and globalization; and it's both socially and economically liberal.
Maryland is the runner-up as it is a highly diverse state with a large, liberal, college educated White population and dominated by globalized industries and governmental agencies. It's not as socially liberal as California, but it is highly supportive of the federal government and globalization.
Choosing a single state for Republicans is difficult. During the Bush II years I would've chosen a Southern state, such as Texas. But today, under Trump, the party is more Rust Belt oriented. I'd say Indiana is the heart and soul of the present GOP. It's a de-industrialized state that has been negatively effected by globalization; socially conservative, but not fundamentalist; highly skeptical of coastal elite and outsiders; and composed largely of white, conservative, working class types.
Agreed about Cali and Indiana.
