For any class M of 4-manifolds, for instance the class M(G) of closed oriented manifolds with pi(1) (M) congruent to G for a fixed group G, the geography of M is the set of integer pairs {(sigma(M), chi(M)) vertical bar M is an element of M}, where sigma and chi denote the signature and Euler characteristic. This paper explores general properties of the geography of M(G) and undertakes an extended study of M(Z(n)).