Begin by rimming your glasses with lime juice and dipping them in salt if desired. Set aside.
In a blender, combine the ice, tequila, lime juice, triple sec, and simple syrup. Blend until smooth and slushy.
Divide the slushy mixture into two bowls. In one bowl, mix in the frozen strawberries until well combined. In the other bowl, mix in the frozen blueberries.
In each prepared glass, layer the strawberry slush on the bottom, followed by the plain slush, and then top with the blueberry slush to create a red, white, and blue effect.
Garnish with lime wedges and serve immediately.