Time has given Dallas enough distance; the majority of residents were either not born or were living elsewhere 50 years ago, and the white-hot figures have either died or moved away. But more important, Dallas has been comfortable publicly grappling with its past in part because what it was then is so different from what it is now.

In 1963, Dallas was the 14th-largest city in the country, with a majority-white population of nearly 700,000, a provincial place whose mostly white, mostly male establishment set the agenda. In 2013, Dallas is the nation’s ninth-largest city, with a majority-minority population of 1.2 million. It is home to the first black district attorney in Texas and the largest urban arts district in the country. Most of the suburbs in the Dallas-Fort Worth region are solidly Republican and bastions of Tea Party conservatives, but Dallas itself leans Democratic. Though President Obama lost Texas in the 2012 election by nearly 1.3 million votes, he handily won Dallas County.

“Dallas is like our country; we are a work in progress,” said Ron Kirk, who served as the city’s first black mayor from 1995 to 2002. “When you look back and reflect on some of the rhetoric that filled our city streets, you do realize that that can target us all, and the actions of a few have the ability to reflect back on all of us.”

The extremism in Dallas in 1963 still thrives in Texas today, though less so in Dallas itself. Back then, commentators on the radio program sponsored by the oil baron H. L. Hunt said that under Kennedy, firearms would be outlawed so people would not “have the weapons with which to rise up against their oppressors.”

This past February, in West Texas, the sheriff in Midland County, Gary Painter, said at a John Birch Society luncheon that he would refuse to confiscate people’s guns from their homes if ordered by the Obama administration and referred to the president’s State of the Union address as propaganda.

Other Texas politicians in recent years have embraced or suggested support for increasingly radical views, including Texas secession, Mr. Obama’s impeachment and claims that the sovereignty of the United States will be handed over to the United Nations. And, of course, it is not just in Texas.