AMP: 0 Location: SR 621 and Plains Rd, Essex No signage as SR 621 begins. 621 is a frontage road between 153 and 154 to facilitate movements to route 9. AMP: 0 Location: SR 621 and Main St, Essex SR 621 ends at CT 154. Turn right for 154 south and left for 154 north. … Continue reading Connecticut State Road 621, (within the CT 9/CT 153/CT 154 interchange)