Based on the House popular vote, the 2018 map would have looked like:
Give or take Florida, Arizona, and Ohio based on Senate races. Texas, Georgia, and North Carolina also would have likely been in play with Trump himself on the ballot given the close margins and swings there.
2006 map would have been very interesting. Could have looked something like this:
Much would depend on the specific candidate running against Bush, of course. But honestly I don't think that map would have been unreasonable for Hillary in 2006 or 2008.
