Secession fever has struck parts of Texas, which Mitt Romney won by nearly 1.3 million votes.

Sales of bumper stickers reading “Secede” — one for $2, or three for $5 — have increased at TexasSecede.com. In East Texas, a Republican official sent out an e-mail newsletter saying it was time for Texas and Vermont to each “go her own way in peace” and sign a free-trade agreement among the states.

A petition calling for secession that was filed by a Texas man on a White House Web site has received tens of thousands of signatures, and the Obama administration must now issue a response. And Larry Scott Kilgore, a perennial Republican candidate from Arlington, a Dallas suburb, announced that he was running for governor in 2014 and would legally change his name to Larry Secede Kilgore, with Secede in capital letters. As his Web page, secedekilgore.com, puts it: “Secession! All other issues can be dealt with later.”

In Texas, talk of secession in recent years has steadily shifted to the center from the fringe right. It has emerged as an echo of the state Republican leadership’s anti-Washington, pro-Texas-sovereignty mantra on a variety of issues, including health care and environmental regulations. For some Texans, the renewed interest in the subject serves simply as comic relief after a crushing election defeat.

But for other proponents of secession and its sister ideology, Texas nationalism — a focus of the Texas Nationalist Movement and other groups that want the state to become an independent nation, as it was in the 1830s and 1840s — it is a far more serious matter. Read on...