Horizontal and vertical differentiation: The Launhardt model

We show how the spatial duopoly proposed by Launhardt in 1885, where firms have access to different transportation technologies, allows one to model in a simple and elegant way the two major types of product differentiation, i.e. horizontal and vertical. We consider the cases where firms are located near the market end points or near the market center. Launhardt's analysis of price determination is then extended by allowing firms to choose strategically their transportation rates. Subgame perfect Nash equilibria involve minimum (maximum) vertical product differentiation when horizontal product differentiation is large (small) enough.