Barley leaf rust, caused by Puccinia hordei, is one of the most important diseases of barley worldwide. The pathogen can readily produce new races that overcome deployed resistance genes (i.e. Reaction to P. hordei or Rph genes) in barley, demonstrating the need to conduct surveys to monitor pathogen virulence. In this study, we characterized the virulence phenotype of 700 P. hordei isolates on 15 Rph genes (Rph1 through Rph15) collected in the United States over a span of 32 years. To analyze virulence patterns, we grouped the country into five geographical regions namely: Pacific/West (PW), Southwest (SW), Midwest (MW), Northeast (NE), and Southeast (SE). Over the 32-year period, high frequencies of virulence (61-91%) were observed for Rph1.a, Rph2.t, Rph4.d, and Rph8.h; intermediate frequencies (17-53%) for Rph3.c, Rph7.g, Rph10.o, Rph11.p, and Rph13.x; and low frequencies (0-10%) for Rph5.e, Rph6.f, Rph9.i, Rph9.z, Rph14.ab, and Regional patterns of virulence were found in the surveys, particularly from 2010-2020. Isolates from the SW, NE, and SE regions had a much higher frequency of virulence for Rph3.c (43-55%) than those from the PW and MW (8-11%). The opposite was true for Rph5.e and Rph6.f where PW and MW isolates had a higher frequency of virulence (22-39%) than those from the SW, NE, and SE (3-5%). The frequency of virulence for Rph7.g in isolates from PW and SW was lower (8-9%) than those collected in the Midwest and the east coast (19-45%). For Rph9.i and Rph9.z, SW isolates had the highest frequency of virulence (33% and 17%, respectively), followed by NE and SE isolates (10.7-16.7% and 14-16%), and then by PW and MW isolates (6-8.7% and 3-8%). Isolates from PW, MW, NE, and SE had a higher frequency of virulence for Rph14.ab (14-22%) than those from the SW (4%). Two predominant virulence associations were detected in the P. hordei population. Isolates that were virulent to both Rph5.e and Rph6.f were more likely to be avirulent to Rph3.c, Rph7.g, and Rph13.x. Likewise, isolates that were virulent to Rph7.g were more likely to be avirulent to Rph5.e and Rph6.f, and to be virulent to Rph13.x. Both virulence associations were prominent in the PW region, where most Washington and Oregon isolates exhibited the former virulence phenotype while most California isolates displayed the latter virulence phenotype. The different virulence phenotypes described in this study will be useful for identifying and characterizing effectors. In decreasing order of effectiveness, (resistant against 100% of isolates), Rph5.e (81%), Rph7.g (67%), Rph9.z (62%), Rph3.c (55%), and Rph9.i (30%) were the most effective Rph genes in the United States. The pyramiding of together with other widely effective Rph and adult plant resistance genes may provide long-lasting resistance against leaf rust of barley in the country. We also screened 441 barley lines from six breeding programs across the United States using a relatively avirulent isolate, 17TX10b, and found that 40% of them were resistant to leaf rust. Gene postulation studies are currently underway to determine which Rph genes these lines may potentially carry.