Thirty-nine-year-old San Antonio native Julián Castro is the youngest mayor of a major American city. First elected mayor of San Antonio in May 2009, Castro handily won re-election in 2011 with nearly 82 percent of the vote. He became a household name after President Obama selected him to deliver the keynote address at the 2012 Democratic National Convention in Charlotte, North Carolina.

Q. In July 2011, you led a San Antonio delegation of businessmen and clergy to Israel. Did the trip have any practical outcome?
A. Absolutely. We signed a friendship-city agreement with Tel Aviv—I believe the first one Tel Aviv had signed in a decade. Our San Antonio water system struck up a memo of understanding with [its counterpart] in Eilat. We found what they are doing with desalinization very impressive, as we are embarking on our own desalinization plant here. They have done amazing things in preserving water, and their creativity and resourcefulness have helped San Antonio better understand its own course at a time when our state is experiencing one of our worst drought crises ever. Also, BioJerusalem and BioMed SA signed an agreement that facilitated new two-way consultations. I have welcomed researchers who came to San Antonio from Israel as a result. One of the most surprising things I learned on the visit was that among the Jewish people the rate of diabetes is roughly equivalent to the very high rate among Hispanic Americans.

Q. Any other lasting impressions from that trip?
A. I vividly recall meeting with Israeli President [Shimon] Peres and specifically…his very wise counsel that we constantly have to understand and assess ourselves and be sure that we are who we want to be, every day. I also remember the beautiful Jerusalem stone on the exterior of every single building in Jerusalem in one variety or another. I gained more of an appreciation of…how much care has been taken to preserve Jerusalem.

Q. Not long before that trip, in April, you cochaired a national conference in San Antonio that brought together Latino and Jewish leaders. What did you discover at that conference?
A. I heard there for the first time about our common aspirations and what is possible in the future. There is a tremendously positive sentiment in the Hispanic community toward Israel, and no less toward the American Jewish community. Both communities know about crossing borders, about struggle, and it was wonderful to be at that conference.

Q. Do you agree with those critics who feel that President Obama, especially during his first term, was chilly to the leaders of Israel?
A. The president is a strong supporter of Israel, and through his leadership the United States has maintained a very close connection [and] has made a very big investment in ensuring that Israel continues to be stable and secure. I know that, particularly around the election, there was a lot of talk about whether the relationship was warm or frosty but, at every possible juncture, he has shown a true support and appreciation for the State of Israel. I am confident this will continue.

Q. President Obama has vowed not to permit Iran to achieve nuclear arms. Do you have confidence this commitment can and will be kept?
A. First, the United States and Israel share a common goal with most of the rest of the world that Iran never secures nuclear weapons. I don’t believe it will happen as long as we are vigilant and remain committed to the goal. The question has arisen recently because of the conversations that President Obama had with Iran’s [President Hassan] Rouhani, and I know that Israel’s Prime Minister Benjamin Netanyahu had some words at the United Nations [in September] about this.

My hope is that any conversations [about] Iran’s future will be done in a productive way. I think that talking can help but, as all the parties recognize, there is a need for verifying what each party has done. This will definitely take more than verbal promises alone. The U.S. will always stand for a strong Israel and ensure that Iran doesn’t have nuclear weapons.

Q. Looking toward the next presidential election, do you foresee the Democrats retaining the White House in 2016?
A. I envision a period of strength for the country economically in the coming years and a period of strength for Democrats politically. My party worked hard in the 2008 and 2012 elections to build a bigger tent. We are, in fact, much bigger in this sense than the Republican Party. There are so many basic challenges now with the Republicans; a minority of the party in effect controls the policy direction of the entire group.

We Democrats seem to enjoy a lot more unity and inclusiveness these days, especially among growing sectors of the population. I believe that the 2016 elections will be good for the Democrats and that we will see another president from our ranks.

Q. Do you agree with those who see you and your city as symbols of the surge in Hispanic influence in America?
A. The Hispanic community will have a deeper level of influence in American politics because of its growing numbers and maturity in terms of voting habits. In 2012, for the first time, we saw Hispanics show up at the polls purposefully to make a significant impact on a policy issue they cared strongly about—immigration reform. I believe [Hispanic] importance will continue to grow along with their numbers and their increased propensity to vote…but what we have to watch is voter participation, and that is not a given. That takes a lot of hard work. It is in the interest of both parties, Republican and Democratic, to understand and mobilize the Hispanic community.

Q. Most Hispanics support the Democrats, but there are also many rising stars from this community in the GOP. Are they exceptions or do they represent a different trend?
A. There is no question that the Republican Party has some good personalities, whether it is Senator Marco Rubio [of Florida] or [Governor Brian] Sandoval from Nevada. The challenge for the Republicans is not the personalities, it’s their policies.
The reason more than 70 percent of Hispanics supported Obama is because, like any sophisticated voter, they saw that his policies more closely reflected what they agree with…. What would concern me is if the Republican Party actually embraced comprehensive immigration reform—and believe me, I hope they do—but that’s the true test.

Q. How do you think the Patient Protection and Affordable Care Act will affect your city?
A. Obamacare offers a golden opportunity to more than 300,000 San Antonians who don’t have health insurance, helping them get it [affordably]. We have [thousands] of people with hypertension, diabetes, obesity issues, and too often they find the hospital emergency room is their primary care physician. They will now have the opportunity to engage in preventive health care, instead of waiting for a catastrophic health crisis to strike.

Q. Do you expect San Antonio to become a major gateway to Mexico and Latin America?
A. The long-term goal for San Antonio is to become the third gateway city to Latin America, along with Los Angeles on the West Coast and Miami on the East Coast. Those two are already quite successful in terms of trade relationships, visitors going back and forth, businesses spanning both sides of the border. San Antonio is not quite at that level yet, but we are rapidly growing in influence and importance.

We’ve seen our exports go up. We’ve seen thousands of Mexicans purchase second homes in San Antonio, folks who have started businesses. Our largest private sector employer, H-E-B supermarket, has about 75,000 employees statewide, and it recently [opened for business] in Mexico, with thousands of employees.

There is already robust trade [with Mexico] that emanates from San Antonio.… We have seen the number of nonstop flights between San Antonio and Mexican cities increase from a few a week to over 50.… San Antonio is growing tremendously.