A method for partitioning a genome is provided. In certain embodiments, the method comprises: a) nicking a region of the genome using a sequence-specific nicking endonuclease to produce a nicked double-stranded genomic region; b) hybridizing the nicked double-stranded genomic region with an oligonucleotide comprising: i. an affinity tag; and ii. a nucleotide sequence that is complementary to the nucleotide sequence that is immediately adjacent to the nick site, to produce a duplex in which a terminal nucleotide of the oligonucleotide lies immediately adjacent to said a nucleotide of the nick site; c) ligating the terminal nucleotide of the oligonucleotide to the nucleotide of the nick site to produce a ligation product; and d) separating the ligation product from unligated products using the affinity tag. Compositions and kits for practicing the method are provided.