Shake all but soda with ice.
Top with soda.
Garnish with peach slices.
A highball cocktail is just a fancy name for whiskey and any type of mixer. Traditionally served over ice in a large, straight-sided Collins glass, the cocktail is over a century old and the question of who first served one is a mystery. Some folks say it was brought to the United States by an English actor. Some say it was created by a bartender strapped for ingredients. All we know is this one is made for summer.