The nation’s yearlong deliberation over immigration has taken a head-snapping detour.

What was once a debate over how to fix a broken system and provide a path to citizenship for millions has become a race to decide how to increase border patrols and send people back quickly to their country of origin.

The sudden rise in the number of families and unaccompanied minors from Central America crossing the border has refocused attention on immigration, but hardly under the terms that President Barack Obama and immigrant advocates once envisioned.

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Some questions and answers about how we got to this upended state of affairs:

Q. Haven’t illegal border crossings been dropping?

A. Yes. From 1990 to 2007, apprehensions by the Border Patrol of people crossing illegally averaged nearly 1.17 million a year; some of the highest were from 1998 to 2000. By 2012, they had dropped to nearly 365,000. According to the Pew Hispanic Center, the number of unauthorized immigrants in the U.S. rose from an estimated 3.5 million in 1990 to a peak of 12.2 million in 2007. The number then fell to 11.3 million in 2009 and has remained statistically stable since, despite some indications it might be slightly rising.

Q. Where is the increase occurring?

A. The influx is largely by families with children or by minors traveling alone. From October 2012 through the end of last September, the Border Patrol apprehended about 24,000 unaccompanied children at the border. But between October and the end of this June, the number shot up to 57,000. Homeland Security Secretary Jeh Johnson told Congress that the number is accelerating so fast that it could reach 90,000 by the end of September. Most are coming from El Salvador, Honduras and Guatemala.

Q. Why the focus on children?

A. In 2008, in the waning days of President George W. Bush's administration, Congress passed a law designed to protect children from trafficking by gangs and other criminals. It set up a system to help provide humanitarian relief and possible asylum for children who are victims of trafficking and who face continuing threats back home.

Q. Why such a sudden jump in numbers?

A. Crime, gang violence, poverty across Central America, a desire to reunite with parents or other relatives. White House officials also say smugglers have persuaded families to pay them to bring children to the U.S. by lying to them about their fate in this country.

Q. How does Obama want to deal with the crisis?

A. Obama sent Congress a request for $3.7 billion in emergency spending to increase the number of Health and Human Services facilities for the minors and to tighten border enforcement. Some money would be used to help Central American countries repatriate border-crossers and expand the number of U.S. immigration judges.

Q. What does Congress want to do?

A. Various Republican-driven proposals would change the 2008 law and allow Border Patrol agents to deal with Central American minors in the same way they process Mexican border-crossers. That means they could be turned back immediately if an agent determines the individual has no claim for asylum.