History has marched on since they arrived in the middle of the last century, seeking refuge for what they thought would be a few weeks, but staying for a lifetime.
Around them the Middle East lurched from conflict to civil war to peace and back again. But for Palestinian refugees in these camps, there has been little movement over decades - only their memories and hopes can travel freely back to lost lands.
“UNRWA’S detractors want a solution to the refugee problem without a political agreement,” said Elizabeth Campbell, an UNRWA official in Washington.
“And that’s a very difficult thing to achieve.”