Martin J. Walsh, a Democrat, is the 54th mayor of Boston. The views expressed in this commentary are his own.

(CNN) In Boston, 48% of children have at least one parent who was born outside the United States. I identify with those kids because I was one of them. My mother and father came from Ireland to Boston looking for opportunity. They found their American Dream, and I got to live mine by becoming mayor of the city that embraced us.

My family was far from alone. In Boston, immigrants make up nearly one-third of our population . We welcome and cherish those who are fleeing persecution or simply seeking a better life. We know our success -- and our nation's success -- has always depended on the drive, talent, community and culture of newcomers.

That's why I was so angered by the White House's executive orders this week, aiming to strip cities like Boston of their federal funding and shut the door to desperate refugees . They sent the message that America is rejecting its heritage as a nation of immigrants and giving up on its role as a beacon of hope in the world. More immediately for cities like Boston, these orders threaten to undermine public safety, sap our economic vitality and tear apart our families.

My response has been swift and certain. I stood up -- joined by the dozens of Boston leaders who are first- and second-generation immigrants -- and said that we will not change our values or turn our back on immigrants. I will do everything lawful within my power to protect our immigrant neighbors, documented or not. If necessary, I will use City Hall itself to shelter and protect them from persecution.

I'm hopeful that it won't come to that. The fact is, we have American values, common sense and the United States Constitution on our side.

In the meantime, we'll continue to build trust between law enforcement and immigrant communities. For everyone's safety, both documented and undocumented immigrants need to know they can report crimes without fear of being targeted over civil issues or mere suspicions. The Boston Police Department has worked hard to build this trust while focusing its energies on serious crimes. Cities with "Trust Acts" are among the safest in the United States.

We won't be intimidated by threats to our federal funding, either. The Supreme Court has ruled that federal funds may not be withdrawn over issues unrelated to the funding legislation's purposes. In any case, we won't place money ahead of our neighbors' safety and security.

If we are concerned about economic impacts, we have to recognize how much we depend on immigrants. In Boston, immigrants reflect a significant amount of medical and life science workers; more than one-third of all business owners; and 22% of our university students . Immigrants also contributed $3.5 billion to our city's economy in consumer spending alone.

Nationally, urban regions -- the gateways for immigrants -- account for 91% of America's economic output and total wages.

And regarding this nonsense about a wall, let's be clear: Undocumented southern border crossings have fallen dramatically over the past eight years. A wall is a waste of money, a useless substitute for real reform and a dismal symbol of fear at a time when we need confidence.

The federal government's energy and resources should be aimed instead at solving the serious challenges we face, from healthcare to education to retirement security. Consider what's possible with the White House as our partner. In response to a challenge by former First Lady Michelle Obama, Boston has housed more than 800 homeless veterans since 2014, ending chronic veteran homelessness in our city.

Contrary to the narrative in Washington, for mayors across the country, immigration is an area of bipartisan agreement. At the United States Conference of Mayors last week, leaders from red states and blue states agreed: The actions the White House is threatening would wreak havoc on urban economies and communities.

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Finally, and importantly, these measures cannot be defended by differentiating between documented and undocumented immigrants. First, we reject the cruelty of breaking up families and pulling students out of colleges. More generally, immigrant communities have long blended a variety of legal statuses, because federal immigration law has not kept up with our economy's need for talent and hard work from around the world.

What we need, and what mayors have called for over many years, is comprehensive immigration reform. If Washington continues to fail to deliver on that responsibility, cities will continue to step up. Far from ignoring the challenge, mayors are upholding America's most deeply held values every day.