To keep a level of safety on the road with drivers, pedestrians, bicicylists and other motorists, etc. If you drive too fast or too slow the risk of an accident increases... Obvi.
Speed limits are set by whatever level of government owns that particular roadway.
The four major speed laws typically refer to the laws that regulate speed limits on roadways. These include statutory speed limits set by laws, prima facie speed limits that allow flexibility based on conditions, fixed or regulatory speed limits posted on signs, and basic speed laws that require drivers to always operate at a safe speed regardless of posted limits.
The European Union allow its constituent nations to set their own speed limits.
The federal government sets national speed limits by promising monetary incentives to states that cooperate with their legislature. The states can set their own limits but if they want aid from the federal government they must comply with their mandates.
The people who set the speed limits create and those who would break them.
Statutory speed limits are set by law and vary depending on the type of road. Advisory speed limits are recommended speeds for safe driving in certain conditions, such as sharp curves or inclement weather. Variable speed limits change based on real-time traffic conditions, enforced through electronic signs on highways.
They mean if you drive over 50 MPH, you will get a speeding ticket.
states
The speed governor is factory set and factory altered. If the owner desires to increase speed the governor can be purchased with out limits.
No, not all 50 states raised the speed limit in 1987. The increase in speed limits was the result of the National Maximum Speed Law being repealed in that year, allowing states to set their own speed limits. Some states did choose to raise their speed limits, but not all 50 states implemented higher speed limits in 1987.
Varies by state. Usually 0mph. Usually states set their own limits just like they set their own speed limits. Also many if not all states will preempt a minimum speed if doing such a speed is going to cause a collision. Samples: Connecticut: 40mph minimum, preempted if congestion or traffic is ahead. Rhode Island: Speed Limit-10mph, allows drivers to set speed limit based on road conditions.
That varies between states, who have jurisdiction to set speed limits in their respective state.