In preparation for deep extragalactic imaging with the James Webb SpaceTelescope, we explore the clustering of massive halos at z = 8 and 10using a large N-body simulation. We find that halos with masses of109-1011 h -1 M ☉, which arethose expected to host galaxies detectable with JWST, are highlyclustered with bias factors ranging from 5 to 30 depending strongly onmass, as well as on redshift and scale. This results in correlationlengths of 5-10 h -1 Mpc, similar to those of today’sgalaxies. Our results are based on a simulation of 130 billion particlesin a box of size 250 h -1 Mpc using our new high-accuracyABACUS simulation code, the corrections to cosmological initialconditions of Garrison et al., and the Planck 2015 cosmology. We usevariations between sub-volumes to estimate the detectability of theclustering. Because of the very strong interhalo clustering, we findthat a medium-sized survey with a transverse size of the order of 25 h-1 comoving Mpc (about 13′) may be able to detect theclustering of z = 8-10 galaxies with only 500-1000 survey objects if thegalaxies indeed occupy the most massive dark matter halos.