Maximum speed for national speed limit?

driving dropping friend off after work , came across sign had white round , black line going across, know maximum speed 70mph, friend told me 'umlimited speed' know thats not true otherwise of hit 130 :$ can explain me....properly.

basically driving dropping friend off after work , came across sign had white round , black line going across, know maximum speed 70mph, friend told me 'umlimited speed' know thats not true otherwise of hit 130 :$ can...

Cars & Transportation Safety Next