I posted a script above to get a sorted rank. This other one gets you the aggregate numbers for US:

    [...document.querySelectorAll('.fatitem table .athing')].map(el => [el.textContent.trim(), el.nextSibling.textContent.trim()]).reduce((a, [c,s]) => c.startsWith('US') ? a + parseInt(s) - 1 : a, 0)

As of this comment, there are around 10 times more votes for US than the second most voted country (Canada). A fourth of those US votes are for California. Meaning, there are twice as many votes for California as there are for Canada.

This suggests that Silicon Valley still represents a significant portion of the HN community.