R.I. Gen. Laws § 31-14-6
Local authorities in their respective jurisdictions may in their discretion, but subject to § 31-14-8, authorize by ordinance or by authority granted to any organized traffic engineering department, higher prima facie speeds than those stated in § 31-14-2 upon through highways or upon highways or portions of highways where there are no intersections or between widely spaced intersections, which higher prima facie speed shall be effective at all times or during hours of daylight or at any other times that may be determined when signs are erected giving notice of the authorized speed. Local authorities shall not have authority to modify or alter the basic rule set forth in § 31-14-1 or in any event to authorize by ordinance a speed in excess of fifty miles per hour (50 mph) during the daytime or forty-five miles per hour (45 mph) during nighttime.
R.I. Gen. Laws § 31-14-6