On Fri, Nov 7, 2014, I (Christof Teuscher) set out for an unsupported attempt of the Joshua Tree traverse. The attempt was announced beforehand: www.teuscher.ch/aagaa/announcement-unsupported-joshua-tree-traverse-attempt.
The route is 37.3 mi long with about 3,200ft of elevation gain and 4,300ft of elevation loss. It starts at the Black Rock Campground, traverses the park, and ends at the North Entrance Station. My attempt was completely unsupported, i.e., I carried all my food and water. No crew or caches were used. The reduce my need for water, I ran entirely throughout the night. I started at 7pm on Fri, Nov 7, 2014, and finished in 7:12:50. I believe this is a new unsupported FKT.
Strava log: www.strava.com/activities/216759716
To the best of my knowledge, the previous self-supported Only-Known Time (OKT)/Fastest-Known Time (FKT) was 7h49min. The group run was self-supported; they had at least one supply point at Juniper Flats (mile 20). Their report is available here www.enduranceguy.com/2012/06/03/jtree-traverse-running-across-joshua-tree-national-park. It was also mentioned here: running.competitor.com/2014/09/photos/8-epic-running-adventures-americas-national-parks_113218.