Demonstrators crowded into parks and plazas across the U.S. Saturday to rally against President Donald Trump as officials urged calm and mobilized National Guard troops ahead a military parade to mark the Army's 250th anniversary that coincides with the president's birthday.

Tens of thousands of Americans are marching through the US's major cities in the largest protest effort against Donald Trump since his re-election in January.

There's been a heavy crackdown in Los Angeles after more than a week of protests over US immigration raids. Federal police had been targeting undocumented migrants in workplaces across the city. In a marked escalation,