BECKLEY, W.Va.—President Barack Obama eulogized 29 coal miners who died in an explosion in the nearby Upper Big Branch Mine in a speech that avoided assigning blame for the disaster.

Before the president spoke, grieving families of the dead filed into a convention center here on Sunday as the men's names were read out loud. The audience applauded for each one and a member of each family placed a miner's helmet atop one of 29 white crosses standing in a row at the foot of the stage.

"Nothing...