In 1998 the state of Chihuahua moved from Central time to Mountain time. This is likely because Ciudad Juárez is directly across the border from El Paso, Texas, which is on Mountain Time. Later, in 2001, Mexico experimented with a shorter daylight saving period from the first Sunday in May to the last Sunday in September, returning to the previous seven-month schedule in 2002. Nevertheless, since Mexico City and other southern states decided to use again the shorter five-month daylight saving period in 2002, the Mexican Congress ruled that this decision was a federal one, and so it has to be ruled by the same congress. This decision backfired when the United States extended their DST period in 2007, because the Mexican Congress now refused to do the same for Mexico, under the strong influence of the southern states representatives. Two years later, the population of the northern border cities complained about the time difference between those cities and their US counterparts and their government requested the DST extension again. For the second time, Congress refused to adopt it nationwide. As a result, only the areas within 20 km of the United States border, as well as all of Baja California, began observing DST on the US schedule in 2010, while the rest of the country retained the pre-2007 United States DST schedule. A new bill was proposed in September 2015 for the rest of the country to also observe DST on the extended 2007 US schedule, thus eliminating the distinction between the border cities and the rest of Mexico. Congress refused to approve the change for the third time in a 10-year period, discarding the bill on June 29, 2016.