Blending ground crumb rubber (CR) with the asphalt binder is an economical and sustainable method of binder modification. The objective of this paper was to evaluate the interaction between the asphalt binder and the three CR types at 170 and 190 degrees C. The three CR types, ambiently ground, cryogenically ground, and Ecorphalt (E-rubber), were blended with a Louisiana conventional PG 67-22 asphalt at two temperatures, 170 and 190 degrees C. The composition of the CR before and after treatment with asphalt was studied using thermogravimetric analysis. Gel permeation chromatography was used to study the molecular weight changes to the asphalt before and after rubber treatment. Fourier transform infrared spectroscopy was used to study the aging characteristics of the CR-modified asphalt binder prepared at the two temperatures. Scanning electron microscopy (SEM) shows the morphology of the rubbers before and after dispersion in the asphalt binder. Performance-grade tests of the CR/asphalt binder blends were used to characterize the rheological properties. E-rubber additive did allow for better dispersion of particles in the asphalt binder at a lower temperature than the other additives evaluated. Ground CR particles were comprised of favorable polyisoprene contents (minimum natural rubber content was 50%) for blending with the asphalt binder. An increase in the blending temperature from 170 to 190 degrees C resulted in a minimal increase in the favorable polyisoprene contents of CR/asphalt binder blends containing 5 and 10% E-rubber, which is likely to influence performance. Favorable polyisoprene contents of the CR/asphalt blends containing 10% ambiently ground CR did not change with the blending temperature, whereas that of the CR/asphalt blend containing 10% cryogenically ground increased with the blending temperature. The CR particles isolated from asphalt blends prepared at 190 degrees C were more swollen than those separated from asphalt blends prepared at 170 degrees C, as measured by SEM. Approximetely 73-87% of the E-rubber particles dissolved in the asphalt binder during blending, confirming that E-rubber had great compatibility with the binder chemistry and, hence, can improve performance.