Texas and Michigan have recently raised their speed limits on highways and freeways and other states may raise theirs soon, according to the Wall Street Journal. Speeds of 55 and 65 mph are now being increased to 70 and 80 mph in certain places. Texas has already started building 80 mph signs along 521 miles of the I-10 and I-20 in western counties, making it the highest speed limit in the U.S. The Department of Energy approximated that every five miles per hour a person drives beyond 60 mph costs an extra 20 cents a gallon, making the fuel-efficiency loss 7 percent to 23 percent, depending on the model of car and gas type. The recent state increases are the latest in speed-limit climbs dating back to the 1995 repeal of the nationwide 55 mph speed limit, according to the Wall Street Journal.