Three local libraries are changing their hours starting next month.

The changes begin Sept. 12 and are the result of information gleaned from monthly activity measures and a recent market study, Pima County Public Libraries said in a news release.

The Joel D. Valdez Main Library, 101 N. Stone Ave., sees little use after 6 p.m. The library will close at 6 p.m., rather than 8 p.m., Mondays through Wednesdays. The library will continue opening at 9 a.m. on those days and will not change its hours for Thursdays through Sundays.

More than half of the users of the Dewhirst-Catalina Library, 15631 N. Oracle Road, are retirees over the age of 65. The library is usually crowded in the mornings, but sees little traffic in the evening. Hours on Tuesdays will shift from 10 a.m. to 7 p.m. to 9a.m. to 6 p.m. . The schedules for the other days of the week will not be changed.

The Sahuarita Library, 725 W. Via Rancho Sahuarita, is near five large schools and serves many families with young children. The library will close on Saturdays, which are the slowest days of the week. The library will open from 10 a.m. to 6 p.m. on Mondays. Under the current schedule, the library is closed on Mondays.

For a list of library locations and hours visit library.pima.gov or call 791-4010.