A rearview mirror element assembly includes an electrochromic reflective element having a primary viewing region operable to exhibit electrically variable reflectivity, with a specularly reflective mirror reflector established at a third surface of a rear substrate at the primary viewing region. An auxiliary viewing region provides an auxiliary wide angle view of a blind spot to the side of a vehicle when the electrochromic reflective element is used in an exterior rearview mirror assembly mounted at a side of a vehicle. A specularly reflective demarcating layer is established at a second surface of a front substrate of the electrochromic reflective element and, at least in part, is visible through the front substrate to a viewer when viewing the first surface of the front substrate of the electrochromic reflective element. The demarcating layer at least partially traverses the reflective element adjacent the auxiliary viewing region.