Immigration experts are warning that California could see a spike in arrivals of unaccompanied children crossing the border this year, following a quiet year in 2015.

Children arriving to the United States often come during the summer, so U.S. Border Patrol numbers from early spring months may be telling about what to expect as arrivals begin increasing, said Adam Hunter, director of the Immigration and the States Project at the Pew Charitable Trusts.

“The numbers are well above this point in 2015 and they’re even higher than this point from 2014, which was a significant surge year,” Hunter said.

Nearly 70,000 children, infants through age 17, arrived by themselves at the U.S. Border in 2014, mostly from Central American countries. In 2015, the numbers dropped off significantly.

Another surge this year could impact states and cities.

“We think of this largely as a federal process, since these are children who are apprehended by federal authorities and border patrol,” Hunter said. But, he added, once children are released from federal shelters, many of them are released to sponsors — often family members or other connections living in the U.S. — all around the country. At that point, children rely on state and city services, like public schools, Hunter said.

So far in this fiscal year, Los Angeles County has taken in the highest number of unaccompanied children of any county nationwide, nearly 1,500. Those children could wait years to resolve their immigration cases.

California still has thousands of legal cases pending from the influx of arrivals two years ago, Hunter said.

In 2014, Governor Jerry Brown put $3 million toward legal nonprofits to aid unaccompanied children in their immigration cases.

Hunter hopes that move, as well as other political action inspired by the 2014 surge, will make states better prepared to handle the arrivals this time around.

“We’re hoping to identify a little more strongly here some of the key roles states and localities can play so they can make informed decisions and be more prepared if in fact these numbers materialize in the summer,” Hunter said.