Will Trump's order reunite families immediately?

(CNN)One is a former hospital. Another is a retrofitted superstore. One is a tent city with the capacity to grow.

These are the places where most infants and children are held after they cross the US-Mexico border without prior authorization.

Children are sent to different facilities across the country depending on their age, gender, history of behavioral issues or criminal activity, or medical needs. These centers are overseen by the Department of Health and Human Services’ Office of Refugee Resettlement, who said the average stay is 56 days.

Some are newly built “tender age” facilities to accommodate the influx of children under 13 who have been separated from their parents under the Trump administration’s zero tolerance immigration enforcement policy. One of those facilities is a former private home about 20 miles from the US-Mexico border in Texas town of Combes, operated by Southwest Key Programs.

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A set of black strollers and a small playground were the only visible signs of some 60 children ranging in age from infants to 10 years old housed inside.

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Others facilities have existed for years as shelters for unaccompanied migrant children who enter the US alone or were separated from their families.

The Homestead Temporary Shelter for Unaccompanied Children in Florida is a former Job Corps site that has been used as a shelter for unaccompanied minors since 2014.

Photos taken this week showed boys and girls at the shelter. On Tuesday, Florida Gov. Rick Scott sent a letter to Health and Human Services Secretary Alex Azar expressing concern over “unconfirmed reports” that the shelter is “potentially holding children who have been forcibly removed from their families.”

In his letter, Scott demanded confirmation of reports…