It varies from state to state. You'd have to specify which state(s) you're referring to.
70mph on some rural interstate highways
70 mph - unless otherwise posted.
70 mph - unless otherwise posted.
70 mph - unless otherwise posted.
Depends which state you're in. Texas has the highest Interstate speed limits, with some sections being allowed up to 80 MPH.
70 MPH on Interstate Highways.
70
69
70 MPH
The maximum speed limit in Florida is 55 mph, except where otherwise posted. Speed limits are 70 mph on some rural interstate highways.
15
70 mph - but some states do not allow that speed.