Time in Oregon - wikipedia Time in Oregon Most of Oregon lies in the Pacific Time Zone ( shown in blue ), except for the northern part of Malheur County ( shown in purple ), which is in the Mountain Time Zone. Time in Oregon is divided into two zones. The vast majority of the state is contained in the Pacific Time Zone. Most of sparsely populated Malheur County, including its largest city, Ontario, and its county seat, Vale, are in the Mountain Time Zone due to their proximity to Boise, Idaho. The time zone division occurs at the southwest corner of township 35 S, range 37 E ( approximately 42.45 degrees north latitude ), continuing east to the state line, then south along the Oregon - Idaho border to the Nevada state line. Drewsey in Harney County is officially in the Pacific Time Zone, but some residents unofficially observe Mountain Time due to proximity to Malheur County. Local businesses and the Oregon Department of Transportation strictly enforce the practice of Pacific Time, however. IANA time zone database In the IANA time zone database, Oregon is contained in two zones : c.c. * coordinates * TZ * comments * UTC offset UTC offset DST Note US + 340308 - 1181434 America / Los_Angeles Pacific Time − 08 : 00 UTC − 07 All except northern 3 / 4 of Malheur County US + 433649 - 1161209 America / Boise Mountain Time - south Idaho & east Oregon − 07 : 00 UTC − 06 Northern 3 / 4 of Malheur County only References Jump up ^ 49 C.F.R. 71.9 : Boundary line between mountain and Pacific zones. Accessed June 25, 2012 External links Richard Cockle ( 2008 - 11 - 02 ). `` Ontario, Ore. : Idaho 's spot to shop ''. The Oregonian. Retrieved 2016 - 05 - 31. Time in the United States States Alabama Alaska Arizona Arkansas California Colorado Connecticut Delaware Florida Georgia Hawaii Idaho Illinois Indiana Iowa Kansas Kentucky Louisiana Maine Maryland Massachusetts Michigan Minnesota Mississippi Missouri Montana Nebraska Nevada New Hampshire New Jersey New Mexico New York North Carolina North Dakota Ohio Oklahoma Oregon Pennsylvania Rhode Island South Carolina South Dakota Tennessee Texas Utah Vermont Virginia Washington West Virginia Wisconsin Wyoming Federal district Washington, D.C. Insular areas American Samoa The Marianas Guam Northern Mariana Islands Puerto Rico U.S. Virgin Islands Retrieved from `` https://en.wikipedia.org/w/index.php?title=Time_in_Oregon&oldid=792785679 '' Categories : Time in the United States by state Geography of Oregon Talk About Wikipedia Add links This page was last edited on 28 July 2017, at 17 : 30. About Wikipedia

Question: why is part of oregon in mountain time
Answer: proximity to Boise, Idaho