use of the two adjoining frequencies of 530 kHz and 1610 kHz. However, on June 8, 1988 an International Telecommunication Union conference held at Rio de Janeiro, Brazil adopted provisions, effective July 1, 1990, to extend the upper end of the AM broadcast band in the Americas, by adding ten frequencies which spanned from 1610 kHz to 1700 kHz. By this time 1610 kHz had been assigned for use by hundreds of Travelers Information Stations in the United States. Moreover, the licensing authority was shared between the FCC and the National Telecommunications and Information Administration (NTIA), so coordination between these two agencies was required. It was concluded that, for operation on 1610 kHz, TIS and broadcasting stations were considered "co-primary" services, thus existing TIS stations were protected from having to move to new frequencies. (This has effectively made it impossible to assign any standard broadcasting stations to 1610 kHz in the United States.) It was also informally suggested that, once most radios could tune to the higher frequencies, all of the TIS stations on 1610 kHz could be moved as a group to 1710 kHz, however this was never implemented. On July 18, 2013, in response to petitions submitted from Highway Information Systems, Inc. (HIS), the American Association of Information Radio Operators (AAIRO), and the American Association of State Highway and Transportation Officials (AASHTO), the FCC adopted Report and Order 13-98 updating and clarifying the regulations applying to TIS stations. The Report and Order, as summarized by a May 2014 Compliance Guide (DA-14-651), approved the establishment of "ribbons" of sequentially located roadside transmitters so long as content remained pertinent at all points. This also clarified that programming content must relate to travel, emergencies or situations of imminent danger to the public, and that it is at the discretion of station operators, based on their knowledge of the area and its population, of what situations present an imminent danger. A subsequent Rule Making procedure, instituted at the request of the AAIRO, resulted in the loosening of the audio frequency limit from 3 kHz to 5 kHz, after it was determined that the improved frequency response would increase intelligibility without increasing interference to stations operating on adjacent frequencies. Although the original proposal suggested completely eliminating the filtering, the 5 kHz standard was adopted as a compromise after the National Association of Broadcasters noted that "full-power AM radio stations routinely use 5 kHz