The same year that Texas won its independence from Mexico, two young and ambitious hucksters arrived from New York of all places and founded a city in the midst of a mosquito-ridden, malarial swamp. One hundred eighty years later, the city named in honor of the hero of San Jacinto continues to thrive and prosper on a scale that no doubt would amaze the brothers Allen (and most everyone since).

It's unfortunate that on your quick cash-and-carry campaign swing today you won't get to see much of that city, soon to be the nation's third-largest - unfortunate because, with due respect to you, Houston represents values and principles that are strikingly antithetical to the divisive, intolerant positions you have loudly and proudly espoused since announcing your candidacy a year ago. This great city could not function if we allowed the hateful attitudes the world is coming to identify as Trumpism to prevail. Neither can this country. Nativist fear, anger, bellicosity - Trumpism, in other words - is not America.

The sprawling place we call the Bayou City is a port, open to the world. The Chronicle wrote a few days ago that the Port of Houston is the nation's largest in foreign waterborne tonnage. More than 8,000 vessels and 200,000 barges move 200 million tons of cargo through the port each year. Those brawny arms open to the world generate jobs for Texans, more than 1.2 million, in fact. As the largest export market in the United States, we're well aware that your straitened, protectionist views on trade and your isolationist inclinations would cost us dearly.

A huge amount of that trade is with a nation you presume to know well: Mexico. Our southern neighbor - and, yes, "neighbor" is the apt word - is the United States' third-largest trading partner; it's second only to Canada as a destination for exports. For both Texas and Houston, Mexico is trading partner No. 1.

Another fact about U.S.-Mexico trade: Many of the manufactured goods that flow across the border are products that U.S. and Mexican firms assemble together in shared supply chains. In a recent Chronicle opinion piece, Andrew Sele of the Woodrow Wilson Center noted that 40 percent of the content in finished goods that Mexico exports to the U.S. is actually made in this country.

And you wonder why Houstonians disdain your rampages about walls, disease-ridden Mexicans and rapists? Trade with our next-door neighbor is one thing, but just as important are a shared culture, cross-border family ties spanning generations and a long border that blends rather than congeals. Those are reasons why your border proposals are anathema.

Houston is a diverse city, more diverse than your hometown, more diverse than Los Angeles. In fact, its jumble of races and nationalities from around the world makes it the most diverse city in America. We are an international megalopolis, a city that "runs about 10, 15 years ahead of Texas, 30 years ahead of the U.S. in terms of ethnic diversity and immigration flows," a Rice University sociologist told the Chronicle not long ago.

When that article was written, by the way, Houston's female mayor was one of the few openly gay politicians in America; our current mayor is African-American. Muslims, Jews, Christians, Buddhists and every other belief under the sun call Houston home. Divisiveness doesn't work in this town.

Houston today is America tomorrow, and the richness, the roiling energy and, yes, the prosperity of an immigrant-welcoming city are what this nation can anticipate if it follows Houston's lead, not yours. Why in the world would Houston - or any other American city - choose to rely on the rancor and divisiveness that your campaign promotes?

You're the fellow who wants to wall us in from the rest of the world, who wants to "protect" us from Muslims, including Syrian refugees desperately seeking respite from a horrendous civil war. We welcome refugees; we welcome their energy and ambition, their earnest desire to make new lives for themselves and their enthusiastic commitment to American values.

Our concern about you - again, with due respect - is that you don't share those values of openness, tolerance and good will. Your attack on an American-born federal judge of Mexican descent, your continuing call for a ban on Muslims and your recent statement questioning President Obama's loyalty to this nation are only the most recent outrages that fuel concern. More and more Americans - Republicans, Democrats and independents - are coming to share that concern.

"Houston is far from perfect," four local faith leaders reminded us in the Chronicle in anticipation of your visit. "We have a yawning chasm between the haves and have-nots. We face environmental challenges, social challenges, educational challenges, even infrastructure challenges, and yet for all that we remain a city relatively free of rancor."

We say: Amen.

We're pleased you've come to Houston, although we wish you could stay a while. A Tex-Mex meal at Ninfa's on Navigation, a stroll through the United Nations that's Bellaire Boulevard or a visit to a mosque or a Hindu temple might offer you a bit of exposure to the open, tolerant, city that we call Houston. That we're proud to call America.

Sincerely,

The Houston Chronicle Editorial Board