Just waiting on Terraform AWS provider to support inter-region VPC peering...

aws-us-east-peering.tf

# Pending apply... needs https://github.com/terraform-providers/terraform-provider-aws/issues/2484
#
resource "aws_vpc_peering_connection" "north-virginia-to-ohio" {
  provider = "aws.us-east-1"
  vpc_id = "${module.us-north-virginia.vpc_id}"
  peer_region = "us-east-2"
  peer_vpc_id = "${module.us-ohio.vpc_id}"

  accepter {
    allow_remote_vpc_dns_resolution = true
  }

  requester {
    allow_remote_vpc_dns_resolution = true
  }

  tags {
    Name = "North Virginia-Ohio VPC Peering Connection"
  }
}

resource "aws_vpc_peering_connection" "ohio-to-north-virginia" {
  provider = "aws.us-east-2"
  vpc_id = "${module.us-ohio.vpc_id}"
  peer_region = "us-east-1"
  peer_vpc_id = "${module.us-north-virginia.vpc_id}"

  accepter {
    allow_remote_vpc_dns_resolution = true
  }

  requester {
    allow_remote_vpc_dns_resolution = true
  }

  tags {
    Name = "North Virginia-Ohio VPC Peering Connection"
  }
}

resource "aws_route" "north-virginia-to-ohio" {
  provider = "aws.us-east-1"
  vpc_id = "${module.us-north-virginia.vpc_id}"
  route_table_id = "${module.us-north-virginia.vpc_routing_table}"
  destination_cidr_block = "${var.aws-ohio-cidr-block}"
  vpc_peering_connection_id = "${aws_vpc_peering_connection.north-virginia-to-ohio.id}"
}

resource "aws_route" "ohio-to-north-virginia" {
  provider = "aws.us-east-2"
  vpc_id = "${module.us-ohio.vpc_id}"
  route_table_id = "${module.us-ohio.vpc_routing_table}"
  destination_cidr_block = "${var.aws-north-virginia-cidr-block}"
  vpc_peering_connection_id = "${aws_vpc_peering_connection.ohio-to-north-virginia.id}"
}