EDIT******* Appears this is outdated info, Some laws have changed,
I ran across this on FaceBook, may be useful to a few.
Alabama
Towing speed limit: 55 mph
Remember this: RV drivers must keep their headlights on at all times when towing in this state.
Alaska
Towing speed limit: 55 mph
Remember this: Essential items which must be carried are flares or reflective signs, fire extinguishers and a gas detector.
Arizona
Towing speed limit: 65 mph
Remember this: Triple towing with a fifth wheeler is permitted here.
Arkansas
Towing speed limit: 65 mph
Remember this: Overnight parking is permitted in rest areas, unless the are signs to the contrary.
California
Towing speed limit: 55mph
Remember this: Any vehicle which is towing is restricted to the right hand lane only.
Colorado
Towing speed limit: 65 mph
Remember this: You are permitted to tow two trailers at the same time here.
Connecticut
Towing speed limit: 55mph
Remember this: RV’s are strictly forbidden to travel in carpool lanes here.
Delaware
Towing speed limit: 55 mph
Remember this: There must be two different ways to be able to apply brakes to both the vehicle and the trailer.
District of Columbia
Towing speed limit: 55 mph
Remember this: RV’s can be no wider than 8 feet.
Florida
Towing speed limit: 65 mph
Remember this: Double or triple towing is not permitted in this state.
Georgia
Towing speed limit: 65 mph
Remember this: Absolutely not permitted to park overnight in rest areas.
Hawaii
Towing speed limit: 55 mph
Remember this: 48 feet is the maximum length for a trailer here.
Idaho
Towing speed limit: 65 mph
Remember this: Passengers are permitted to travel inside truck campers.
Illinois
Towing speed limit: 55 mph
Remember this: In and around Chicago, it is forbidden for trailers to be on boulevards.
Indiana
Towing speed limit: 65 mph
Remember this: 45 feet is the maximum length of an RV here.
Iowa
Towing speed limit: 65 mph
Remember this: Passengers are permitted to travel in fifth wheelers, travel trailers and camper vans.
Kansas
Towing speed limit: 65 mph
Remember this: 14 foot in height is the maximum permitted for RV’s and trailers.
Kentucky
Towing speed limit: 65 mph
Remember this: Regardless of weight, Kentucky does not specifically require brakes on passenger car trailers.
Louisiana
Towing speed limit: 65 mph
Remember this: Passengers are only allowed to travel in pickup campers.
Maine
Towing speed limit: 65 mph
Remember this: Only one boat or travel trailer allowed to be towed at a time.
Maryland
Towing speed limit: 55 mph
Remember this: Liquid propane gas is forbidden in I-95 tunnels.
Massachusetts
Towing speed limit: 55 mph
Remember this: Many parkways in the Boston area forbid trailers.
Michigan
Towing speed limit: 65 mph
Remember this: A minimum tread of 2/32 inches is required on all trailer tires.
Minnesota
Towing speed limit: 65 mph
Remember this: The only triple towing combo allowed is a fifth wheel and a watercraft/ATV/Snowmobile or motorcycle.
Mississippi
Towing speed limit: 65 mph
Remember this: No one is permitted to ride in a fifth wheel, travel trailer or pickup camper.
Missouri
Towing speed limit: 65 mph
Remember this: A braking system only on fifth wheelers is required by law.
Montana
Towing speed limit: 65 mph
Remember this: Flares or reflective signs are required on all RV’s.
Nebraska
Towing speed limit: 65 mph
Remember this: Flares or reflective signs are required on all RV’s.
Nevada
Towing speed limit: 65 mph
Remember this: While drivers and passengers are not permitted to carry open alcoholic beverage containers inside the tow vehicle, they are allowed in the living area of an RV or travel trailer.
New Hampshire
Towing speed limit: 65 mph
Remember this: Overnight parking in any rest area in New Hampshire is strictly prohibited.
New Mexico
Towing speed limit: 65 mph
Remember this: While overnight parking in rest areas is permitted, you are not allowed to stay for more than 24 hours in the same area in any three day period.
New York
Towing speed limit: 55 mph
Remember this: Liquid propane is strictly forbidden in all New York tunnels.
North Carolina
Towing speed limit: 65 mph
Remember this: Travel trailers of 1,000 lbs or more must have their own independent brake system.
North Dakota
Towing speed limit: 65 mph
Remember this: If doing speeds of 25 mph or more, then any trailer must have safety chains attached to the tow vehicle.
Ohio
Towing speed limit: 65 mph
Remember this: If the trailer has an empty weight of 2,000 lbs or more, then brakes are required.
Oklahoma
Towing speed limit: 65 mph
Remember this: Maximum length of any trailer must be under 40 foot.
Oregon
Towing speed limit: 65 mph
Remember this: Self dispensing fuel as garages is not allowed here.
Pennsylvania
Towing speed limit: 55 mph
Remember this: A fully functioning brake system is required for anything that is towed.
Rhode Island
Towing speed limit: 55 mph
Remember this: Overnight parking is prohibited in all rest areas.
South Carolina
Towing speed limit: 65 mph
Remember this: The combined length of both the tow vehicle and the trailer must not exceed 60 feet in length.
South Dakota
Towing speed limit: 65 mph
Remember this: Any vehicle over 8,000 pounds must stop at the weigh stations.
Tennessee
Towing speed limit: 65 mph
Remember this: 8 feet is the maximum permitted width here.
Texas
Towing speed limit: 60 mph during the day, 55 mph at night
Remember this: There is a 24 hour limit to overnight parking in rest areas.
Utah
Towing speed limit: 65 mph
Remember this: RV’s and trailers can be no higher than 14 feet tall.
Vermont
Towing speed limit: 65 mph
Remember this: A usable fire extinguisher must be carried at all times.
Virginia
Towing speed limit: 55 mph
Remember this: Only 2 propane tanks of no more than 20 lbs are permitted per vehicle.
Washington
Towing speed limit: 60 mph
Remember this: While overnight parking is permitted in rest areas, it cannot exceed 8 hours.
West Virginia
Towing speed limit: 65 mph
Remember this: Triple towing is not permitted here.
Wisconsin
Towing speed limit: 65 mph
Remember this: A special permit is required for triple towing.
Wyoming
Towing speed limit: 60 mph
Remember this: While driving at 20 mph you must be able to stop within 40 feet, if you are towing a trailer.
originally from http://www.doityourselfrv.com/state-towing-speeds/