Live updates: US celebrates 250 years despite heat dome; Trump set for ‘long’ speech

Summary

An excessive heat dome is threatening Fourth of July festivities in the nation’s capital and beyond — forcing cancellations, delays and other changes to holiday schedules as millions of Americans head outdoors to celebrate the U.S.’s 250th birthday. Washington, D.C., canceled its annual parade late Friday and pushed back the opening of the “Great American…