diff --git a/moto/ec2/responses/route_tables.py b/moto/ec2/responses/route_tables.py
index 65e9ad144..dde51108d 100644
--- a/moto/ec2/responses/route_tables.py
+++ b/moto/ec2/responses/route_tables.py
@@ -144,6 +144,7 @@ DESCRIBE_ROUTE_TABLES_RESPONSE = """
                   <state>active</state>
                 {% endif %}
                 {% if route.vpc_pcx %}
+                  <vpcPeeringConnectionId>{{ route.vpc_pcx.id }}</vpcPeeringConnectionId>
                   <origin>CreateRoute</origin>
                   <state>blackhole</state>
                 {% endif %}
diff --git a/tests/test_ec2/test_route_tables.py b/tests/test_ec2/test_route_tables.py
index 9df76be2f..6ae266f8d 100644
--- a/tests/test_ec2/test_route_tables.py
+++ b/tests/test_ec2/test_route_tables.py
@@ -240,6 +240,7 @@ def test_routes_not_supported():
 #    new_route = new_routes[0]
 #    new_route.gateway_id.should.be.none
 #    new_route.instance_id.should.be.none
+#    new_route.vpc_peering_connection_id.should.equal(vpc_pcx.id)
 #    new_route.state.should.equal('blackhole')
 #    new_route.destination_cidr_block.should.equal(ROUTE_CIDR)