In this work we present the development of a large set of single nucleotide polymorphisms (SNPs) discovered in two populations of bighorn sheep (Ovis canadensis). To do so we used restriction-site associated DNA (RAD) sequencing of four individuals from each population. Through alignment of reads to the domestic sheep (Ovis aries) genome we discovered >83,000 SNPs, of which >38,000 are suitable for assays such as an Illumina SNP chip. These loci will allow for fine-mapping of loci associated with horn size, and examination of the consequences of the genetic rescue including mapping genes underling differences in life-history characteristics.