Stuck advancing levels

[TroubleOR]

My current level is 175 in the Atomic Age. Despite what I upgrade, I seem to be making no progress towards level 180 (needed to upgrade my City Center and advance to Cold Age).

Any suggestions on the best use of time and resources in order to progress?

 

[Cannibals]

Traps give the speediest XP gain. Then farms and caravans. Generals for the armory.

 

[Intersolar]

Traps give the speediest XP gain.

I would say roads... But yes, economic upgrades aren't really good if you like WWs.

 

[Walker]

Why not good??