It is not. It is hanged vertically. The US flag code states the stars must always be on top.

When displayed either horizontally or vertically against a wall, the union should be uppermost and to the flag’s own right, that is, to the observer’s left. When displayed in a window, the flag should be displayed in the same way, with the union or blue field to the left of the observer in the street.

It is displayed vertically, with the union stars on top, to the left of the observers (the crowd).