ETG galaxy fractions as a function of environment. Left: Our entire sample. Right: ETG fractions in two redshift bins: 1.3 < z < 1.6 (magenta circles) and 1.6 < z < 2.8 (pink circles). We also show with two black circles the fraction for CARLAJ1017+6116 at z = 2.8. The small grey circles and error bars and the dashed line show the morphology-density relation at z ∼ 1 from Postman et al. (2005) and at lower redshift from Dressler (1980). The grey region shows the ±1 σ range of the CANDELS ETG fraction. We observe a significant morphology-density relation up to z ∼ 2. The cluster at z = 2.8 shows a similar fraction of ETGs as in the other clusters, however, one cluster does not provide enough statistics to confirm that the morphology-density relation is already in place at z ∼ 3. In fact, ETG fractions are correlated with environment and increase from high to lower redshift in the intermediate dense regions.