There are no Northern Giant Hornets in Maryland. ('Murder' hornet was a sensationalized moniker made to grab attention).
Those insects have only been found in a couple of places in the Pacific Northwest and Canada.
What you have there is a European Hornet. One of the ways to tell is by the keyhole-like markings on its lower back.

Though large and scary-looking, European hornets are not aggressive if left alone. People tend to notice them in late summer and fall. They are night fliers attracted to light, so if you want to see less of them turn off your outdoor lights and pull your curtains/shades.

You can learn more about them here: 
https://extension.umd.edu/resource/european-hornets

Christine