Leaf lesions typical of those reported for tar spot of corn caused by Phyllachora maydis Maubl. were observed in commercial corn hybrids (Zea mays L.). In 2016, symptoms were observed in Jones County, IA, Palm Beach County, FL, Allegan County, MI, and in Green and Iowa counties, WI. In 2017, symptoms were observed again in Allegan County, MI, and in Grant and Lafayette counties, WI. Leaf signs and symptoms included ascomata, often surrounded by a narrow necrotic halo, on both healthy and senescent leaf material. Disease severity and incidence varied by location. Some fields had few infected plants (<1%), with some infected leaves only exhibiting a single ascoma, whereas in 2017 one field in Michigan had up to 90% infected plants with up to 80% disease severity on individual leaves. Morphological characteristics of the pathogen from all examined leaves from all locations were similar and consistent with the description of P. maydis (Parbery 1967). Ascomata, single or grouped with a clypeus, contained numerous paraphyses, with cylindrical asci containing hyaline, ellipsoid, aseptate ascospores 5.5 to 8 × 9.5 to 14 µm (n = 30). DNA was extracted from ascomata aseptically removed from leaves collected in each state. Voucher samples from each state were deposited in the U.S. National Fungus Collections (BPI). The internal transcribed spacer (ITS) regions of the ribosomal RNA gene were sequenced using primer pair ITS1F/ITS4A (Larena et al. 1999) for Iowa and Michigan samples and ITS4/ITS5 for Wisconsin (White et al. 1990). Sequences from Iowa, Michigan, and Wisconsin were identical and showed a 97% sequence homology to GenBank deposit accession KU184459.1, with a 90% query cover. A representative sequence from each state was deposited: Iowa (BPI 910561) GenBank MG881848, Michigan (BPI 910562) GenBank MG881847, and Wisconsin (BPI 910560) GenBank MG881846. Sequences were not obtained from the Florida sample (BPI 910568). Koch’s postulates were not performed given the obligate nature of the pathogen (Muller and Samuels 1984). This report documents the first confirmation of tar spot on corn in Iowa, Michigan, and Wisconsin (three states surrounding Indiana and Illinois, where it was first reported in 2015; Ruhl et al. 2016) and Florida. It has been reported in Central and South America that when coinfection of P. maydis and Monographella maydis occurs there can be significant yield loss. However, M. maydis has not yet been documented within the United States. There may currently be no significant losses in grain production; however, this disease could potentially affect silage corn production for which early dry-down is not desired, and it may increase lodging.