Ce n'est pas une question de Mammoth ou Bishop c'est que cette route
http://maps.google.fr/maps?f=d&source=s_d&saddr=Vall%C3%A9e+de+Yosemite, +Californie+95389, +%C3%89tats-Unis&daddr=Lee+Vining, +CA, +United+States&hl=fr&geocode=FeXqPwId52rf-CmvY_I4_vGWgDFu4slULj8hGQ%3BFTEvQwIdaFjm-CnZRzvcVjaWgDHrG1eRYFcz0A&mra=ls&sll=37.868891, -119.102097&sspn=0.474291,0.792389&ie=UTF8&ll=37.835276, -119.459152&spn=0.474508,0.792389&z=11 est fermée et les autres
http://maps.google.fr/maps?f=d&source=s_d&saddr=Vall%C3%A9e+de+Yosemite, +Californie+95389, +%C3%89tats-Unis&daddr=38.34071, -119.82486+to:Lee+Vining, +CA, +United+States&hl=fr&geocode=FeXqPwId52rf-CmvY_I4_vGWgDFu4slULj8hGQ%3BFWYISQIdJJ7b-Cmhk_vbV0KXgDFRHCWa5alcnA%3BFTEvQwIdaFjm-CnZRzvcVjaWgDHrG1eRYFcz0A&mra=dpe&mrcr=0&mrsp=1&sz=10&via=1&sll=38.087013, -119.669952&sspn=0.945761,1.584778&ie=UTF8&z=10 ,
http://maps.google.fr/maps?f=d&source=s_d&saddr=Vall%C3%A9e+de+Yosemite, +Californie+95389, +%C3%89tats-Unis&daddr=38.47992, -120.014+to:Lee+Vining, +CA, +United+States&hl=fr&geocode=FeXqPwId52rf-CmvY_I4_vGWgDFu4slULj8hGQ%3BFTAoSwIdULvY-CnlSZwUfv2ZgDHdKbg_PHqcUg%3BFTEvQwIdaFjm-CnZRzvcVjaWgDHrG1eRYFcz0A&mra=dvme&mrcr=0&mrsp=1&sz=10&via=1&sll=38.368579, -119.819641&sspn=0.942107,1.584778&ie=UTF8&z=10 ,
http://maps.google.fr/maps?f=d&source=s_d&saddr=Vall%C3%A9e+de+Yosemite, +Californie+95389, +%C3%89tats-Unis&daddr=38.63743, -120.14223+to:Lee+Vining, +CA, +United+States&hl=fr&geocode=FeXqPwId52rf-CmvY_I4_vGWgDFu4slULj8hGQ%3BFXaPTQIdasbW-ClFxmatM_aZgDH6sMjvN1PMHg%3BFTEvQwIdaFjm-CnZRzvcVjaWgDHrG1eRYFcz0A&mra=dvme&mrcr=0&mrsp=1&sz=10&via=1&sll=38.368579, -119.819641&sspn=0.942107,1.584778&ie=UTF8&z=10 plus au nord aussi, il faut donc envisager de passer au sud de la Sierra par Bakersfield
http://maps.google.fr/maps?f=d&source=s_d&saddr=Vall%C3%A9e+de+Yosemite, +Californie+95389, +%C3%89tats-Unis&daddr=35.39578, -119.0449+to:Furnace+Creek, +Californie, +%C3%89tats-Unis&hl=fr&geocode=FeXqPwId52rf-CmvY_I4_vGWgDFu4slULj8hGQ%3BFcQYHAId3ITn-Cnhengz1mnqgDE-kPduvlrOrQ%3BFRROLAIdGrEI-SlzXfVWBz_HgDE26Fu74GJILQ&mra=dpe&mrcr=0&mrsp=1&sz=9&via=1&sll=35.933541, -118.067322&sspn=1.945843,3.169556&ie=UTF8&z=9 ou plus au nord pratiquement par South Lake Tahoe
http://maps.google.fr/maps?f=d&source=s_d&saddr=Vall%C3%A9e+de+Yosemite, +Californie+95389, +%C3%89tats-Unis&daddr=38.78901, -120.15433+to:Furnace+Creek, +Californie, +%C3%89tats-Unis&hl=fr&geocode=FeXqPwId52rf-CmvY_I4_vGWgDFu4slULj8hGQ%3BFZLfTwIdJpfW-CnP4ovffoqZgDEx0ocaA1B79w%3BFRROLAIdGrEI-SlzXfVWBz_HgDE26Fu74GJILQ&mra=ls&via=1&sll=38.608286, -119.63974&sspn=0.938979,1.584778&ie=UTF8&z=8 pour rejoindre Death Valley.
Pour Grand Canyon en avril seule la rive sud est ouverte, le trajet est alors celui-là : Las Vegas/Hendreson (?) Grand Canyon, Monument Valley, Page, Bryce, Las Vegas, Los Angeles.
http://maps.google.fr/maps?f=d&source=s_d&saddr=Las+Vegas, +Nevada, +%C3%89tats-Unis&daddr=Tusayan, +AZ, +United+States+to:Route+inconnue+to:Page, +AZ, +United+States+to:63+Bryce+Canyon+National+Pk, +Bryce+Canyon, +84764, +United+States+(Bryce+Canyon+Lodge)+to:Las+Vegas, +Nevada, +%C3%89tats-Unis&hl=fr&geocode=FdYQJwIdMJoi-SnRffWkgre-gDGjebPV5tXMOg%3BFdvpJAIdoxVR-SmJKnYt8BszhzFfNWkMArRa_g%3BFZ5ONAId-s5v-Q%3BFSJGMwIdp1Fb-SmPdc39WxM0hzE5TjhTUS-Ybg%3BFZgHPgId6GVQ-SGN3CYvrlONeA%3BFdYQJwIdMJoi-SnRffWkgre-gDGjebPV5tXMOg&mra=pd&mrcr=3,4&sll=36.79609, -112.763672&sspn=3.848497,6.339111&ie=UTF8&ll=36.452218, -112.648315&spn=3.865692,6.339111&z=8
Possibilté de faire Page, Monument Valley, Bryce, Las Vgeas , mais en prenant le ferry pour traverser le Lake Powell à Hall's Crossing mais grosse ��tape et quelques miles sur des pistes.
http://maps.google.fr/maps?f=d&source=s_d&saddr=Las+Vegas, +Nevada, +%C3%89tats-Unis&daddr=Tusayan, +AZ, +United+States+to:Page, +AZ, +United+States+to:Route+inconnue+to:37.4537861, -110.679675+to:37.77135, -110.93784+to:63+Bryce+Canyon+National+Pk, +Bryce+Canyon, +84764, +United+States+(Bryce+Canyon+Lodge)+to:Las+Vegas, +Nevada, +%C3%89tats-Unis&hl=fr&geocode=FdYQJwIdMJoi-SnRffWkgre-gDGjebPV5tXMOg%3BFdvpJAIdoxVR-SmJKnYt8BszhzFfNWkMArRa_g%3BFSJGMwIdp1Fb-SmPdc39WxM0hzE5TjhTUS-Ybg%3BFaVONAId3M5v-Q%3BFdp_OwIdhSln-SmNBOS4Z_U2hzEV29W0OlDVfQ%3BFVZYQAIdEDlj-SkDTxgYQQ02hzE96SYLASXfIQ%3BFZgHPgId6GVQ-SGN3CYvrlONeA%3BFdYQJwIdMJoi-SnRffWkgre-gDGjebPV5tXMOg&mra=ls&via=4,5&sll=37.758773, -111.016846&sspn=0.474999,0.792389&ie=UTF8&z=8
Patrick