Would there be freedom of movement between Texas and the U.S.?

Almost certainly yes, in practical terms, because that is what serves both countries, and the models for it already exist and work. Whether through keeping US citizenship, streamlined travel cards, or a formal movement arrangement, the realistic outcome is that people keep crossing between Texas and the United States with minimal friction. The exact form is negotiated; the direction is not in serious doubt.

For many Texans, movement stays totally free because they keep US citizenship

The simplest path to free movement is the one a lot of Texans already have. Texas independence does not strip US citizenship, so many Texans would remain dual citizens, and a dual citizen moves between Texas and the United States with no restriction at all. For them, "freedom of movement" is not even a question to negotiate; it is a right they keep. The dedicated live answer explains how US citizenship is retained.

Free, friendly movement between neighbors is the norm, not the exception

Look at how the world actually works and easy movement between contiguous, friendly nations is ordinary. The United States already lets more than a million people a day cross its border with Mexico, many using only a Border Crossing Card rather than a passport. It runs a Visa Waiver Program that lets citizens of dozens of countries travel for business or tourism without a visa. The live answers on travel and the border walk through how smoothly a Texas-US border can function, using the long, friendly US-Canada boundary as the template. Friction is a political choice, and neither side has a reason to choose it.

There is a formal model for exactly this: the Common Travel Area

If the two countries wanted to go further than streamlined travel and formalize genuine freedom of movement, there is a proven template. Ireland and the United Kingdom run a Common Travel Area, under which Irish and British citizens move freely and live in either country with no visa and no work permit, and with the right to work, study, and use public services. It dates back to 1922, when Ireland became independent, it predates both countries joining the European Union and never depended on it, and the two governments reaffirmed it in 2019. Here are two close neighbors, one of which became independent from the other, who chose deep freedom of movement and have kept it for a century. That is a live, working example of precisely the kind of arrangement Texas and the United States could build.

The economics push hard toward openness

The reason to expect easy movement is not optimism; it is interest. The Texas-US relationship is one of the most economically integrated on earth, with people commuting, doing business, visiting family, and trading across the line constantly. Both governments have an overwhelming incentive to keep that movement flowing, because choking it would damage both economies. The same deep integration opponents call a reason Texas "cannot" leave is in fact the strongest guarantee that movement stays open after it does.

What is honestly still to be negotiated

We will not overstate it. The precise legal form of movement between an independent Texas and the United States, visa-free travel, a Common-Travel-Area-style arrangement, or some tailored mix, is part of what the two countries negotiate in the separation. The terms are theirs to set. What the record supports is the direction: keeping US citizenship makes movement free for many Texans outright, proven models exist for the rest, and the mutual interest in openness is enormous.

The bottom line

Expect movement between Texas and the United States to stay easy. Many Texans keep free movement automatically by keeping US citizenship, friendly neighbors routinely make crossing simple, and there is a century-old working model, the Ireland-UK Common Travel Area, for formal freedom of movement between an independent nation and the country it left. The exact terms are negotiated; the practical result is open borders for people, by mutual interest.