Lars Ortiz: My name is Lars Ortiz, and I'm the author of Walls and Welcome Mats: Immigration and the American Dream.

I got the idea to write this book because in recent years I ran into some people who were saying some pretty hurtful things about immigrants. I even heard those kinds of nasty things being said in the news by politicians, and that made me think about my own family. One of my parents was an immigrant, born and raised in Mexico, and my other parent's ancestors came from Norway in the 1800s. I also thought about my old middle school students. Would they say those same mean things about Salvador, Maria, or Abdullahi?

As I researched the book, I realized people have been coming to this country since it began. In fact, America was founded by immigrants. That's why the United States is often called "a nation of immigrants." But why do immigrants come to our shores, and from where? Have immigrants always faced a backlash from the people already here? Why are some people so mean to and fearful of immigrants? There had to be an explanation. Well, I explore all of those topics and more.

I'm now going to read some of the introduction from my book.

Why are some Americans unwelcoming to new immigrants? Some fear people who are different. They see unfamiliar people as strange, or scary, or as an 'other.' Some people fear that immigrants will take their jobs. Others blame immigrants for society's problems. Divisive words by politicians can increase a dislike or fear of people from other countries.

Some natural-born citizens, people born in the United States, claim that immigrants are a drain on U.S. resources and the economy. This is untrue. Immigrants contribute greatly to the economy and the culture of the United States. Over the centuries, immigrants have built railways and highways, dug canals, and worked in mills, mines, and factories. Immigrants have always been the backbone of the U.S. economy. From science and technology to the arts and politics, immigrants and the children of immigrants have proven to be some of the most ambitious and creative people in the country.

Almost every American has an immigration story to tell, whether they moved here yesterday or their ancestors arrived hundreds or even thousands of years ago. As we explore the history of immigration, think about your story. When did your journey begin? Why did your family move to where you live? When they arrived, did they encounter walls trying to stop them or welcome mats making them feel at home? If you don't already know the answer to these questions, it might be worth investigating your roots and ancestry by making a family tree, researching old photos and documents, interviewing relatives, or maybe taking a DNA test. What is your immigration story?