Svalbard is as close as you can get to a place with open borders
I think the degree to which open borders are a reality within the U.S. is under-appreciated. As a reminder, U.S. states are sovereign entities with their own criminal laws, tax regimes, educational systems, property and contract rights, civil rights, economic growth, industries, natural resources, etc. In some cases their laws are pre-empted by U.S. federal law, but there remains quite a bit of diversity.<p>Despite this, U.S. residents can travel or move anywhere they want within the 50 states, with no prior approval and relatively inconsequential paperwork that largely amounts to notifying local authorities after the fact.<p>Given this, I think it&#x27;s surprising, and somewhat illuminating, the degree to which population, cultural, and economic differences persist across generations. The states with the highest (MD) and lowest (WV) median household incomes are directly adjacent to one another, but WV has not been emptied by mass migration into MD. Plenty of Oregon residents complain about income taxes, but don&#x27;t move next door to Washington, which does not have an income tax. Etc.<p>I know it&#x27;s not the same as international borders, but it&#x27;s also more significant than a single national government with purely administrative regions. Thinking about this has led me to question some of the fears about open international borders.