KANSAS CITY, Mo. -- High school senior Adrian Morales and his friends have been hearing the same message ever since their parents brought them illegally to the United States and to Kansas City as young children:

Work hard, do well in school and someday, if luck and politics allow, some form of the American Dream of job and success might be yours.

Now, today — the first in which undocumented young people like Adrian, 16, can file to legally remain in the country under a new immigration policy — he and friends finally feel the words are true.

“It’s a big deal,” Morales, 16, of the Alta Vista Charter School said Tuesday. “You can work legally. You can go to college.”

Although the new policy offers opportunities, it also comes with widespread concerns and questions, the most pressing of which centers on the fact that the policy, in a new administration, could be overturned as easily as it was implemented.

Two months ago, on June 15, President Barack Obama announced the policy, officially called “deferred action for childhood arrivals.” Because the policy does not offer a path to citizenship or to a permanent residency “green card,” it is often referred to as a watered-down version of the proposed Dream Act, which would provide both to undocumented young people.

Instead, the deferred-action policy provides a way to legally stay and work in the United States to individuals who are residing here unlawfully and who entered the country as children. From its start, the policy was controversial, with critics of more open immigration laws and policies immediately decrying it as a presidential end-run around Congress.

Under the policy, applicants must be under age 31 as of June 15 and must have arrived in the country before they turned 16. They can have no felony convictions or serious or repeated misdemeanor convictions. They also must show that they are either in school, have graduated from high school, earned a GED or been honorably discharged from the U.S. military.

Those who meet the criteria will receive a document that allows them to legally reside and work in the United States for two years. The document is renewable indefinitely upon review.

Over the last 60 days, the Department of Homeland Security has been gearing up for what is expected to be a deluge of as many as 800,000 applications nationwide, although some immigration groups estimate the number will be 1.7 million or more.

“We’re prepared. We’re prepared for any volume that may come in,” an immigration official said in a teleconference Tuesday.

In Kansas City, as throughout the nation, immigration groups and lawyers also have been preparing for this day.

At Alta Vista, a largely Hispanic school just west of Downtown, Morales’ classmates Benjamin Damian, 16, Dulce Vazquez, 17, Silvia Zavala, 17, and Yessenia Merida, 17, all said they were excited to apply. All said they were between ages 4 and 11 when they were brought to the United States by parents.

Beyond attending high school, each student also takes courses at Penn Valley Community College to earn early credits toward college. Until today, they said, each lived with the prospect of attending college, but then, because they are undocumented, they also knew it was unlikely that they would ever be able to use their degrees to hold a job in the United States.

“This is a huge deal,” Merida said. “For me, it changes a lot.”