America/Boise

Time zone identifier: America/Boise

Current civil offset: -07:00 (MST)

Current DST state: Observing Standard Time

First standard time adoption: Adopted on 1883-11-18

Local Mean Time (LMT): -07:44:49 based on geographic meridian

Total recorded transitions: 151 transitions across 4 distinct offsets

Associated countries: US

Historical Offset Step Chart (1880 to Present)

Text summary: America/Boise shifted between 4 distinct offsets from 1883-11-18 through the modern era.

Complete Transition History (151 Transitions)

UTC Instant	Local Wall Time	Shift	Abbreviation	DST	Effect
`1883-11-18T20:00:00Z`	`1883-11-18 12:00:00`	-07:44:49 → -08:00	`PST`	No	overlap
`1918-03-31T10:00:00Z`	`1918-03-31 03:00:00`	-08:00 → -07:00	`PDT`	Yes	gap
`1918-10-27T09:00:00Z`	`1918-10-27 01:00:00`	-07:00 → -08:00	`PST`	No	overlap
`1919-03-30T10:00:00Z`	`1919-03-30 03:00:00`	-08:00 → -07:00	`PDT`	Yes	gap
`1919-10-26T09:00:00Z`	`1919-10-26 01:00:00`	-07:00 → -08:00	`PST`	No	overlap
`1923-05-13T10:00:00Z`	`1923-05-13 03:00:00`	-08:00 → -07:00	`MST`	No	gap
`1942-02-09T09:00:00Z`	`1942-02-09 03:00:00`	-07:00 → -06:00	`MWT`	Yes	gap
`1945-08-14T23:00:00Z`	`1945-08-14 17:00:00`	-06:00 → -06:00	`MPT`	Yes	offset-only
`1945-09-30T08:00:00Z`	`1945-09-30 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`1967-04-30T09:00:00Z`	`1967-04-30 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`1967-10-29T08:00:00Z`	`1967-10-29 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`1968-04-28T09:00:00Z`	`1968-04-28 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`1968-10-27T08:00:00Z`	`1968-10-27 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`1969-04-27T09:00:00Z`	`1969-04-27 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`1969-10-26T08:00:00Z`	`1969-10-26 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`1970-04-26T09:00:00Z`	`1970-04-26 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`1970-10-25T08:00:00Z`	`1970-10-25 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`1971-04-25T09:00:00Z`	`1971-04-25 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`1971-10-31T08:00:00Z`	`1971-10-31 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`1972-04-30T09:00:00Z`	`1972-04-30 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`1972-10-29T08:00:00Z`	`1972-10-29 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`1973-04-29T09:00:00Z`	`1973-04-29 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`1973-10-28T08:00:00Z`	`1973-10-28 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`1974-02-03T09:00:00Z`	`1974-02-03 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`1974-10-27T08:00:00Z`	`1974-10-27 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`1975-02-23T09:00:00Z`	`1975-02-23 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`1975-10-26T08:00:00Z`	`1975-10-26 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`1976-04-25T09:00:00Z`	`1976-04-25 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`1976-10-31T08:00:00Z`	`1976-10-31 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`1977-04-24T09:00:00Z`	`1977-04-24 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`1977-10-30T08:00:00Z`	`1977-10-30 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`1978-04-30T09:00:00Z`	`1978-04-30 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`1978-10-29T08:00:00Z`	`1978-10-29 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`1979-04-29T09:00:00Z`	`1979-04-29 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`1979-10-28T08:00:00Z`	`1979-10-28 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`1980-04-27T09:00:00Z`	`1980-04-27 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`1980-10-26T08:00:00Z`	`1980-10-26 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`1981-04-26T09:00:00Z`	`1981-04-26 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`1981-10-25T08:00:00Z`	`1981-10-25 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`1982-04-25T09:00:00Z`	`1982-04-25 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`1982-10-31T08:00:00Z`	`1982-10-31 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`1983-04-24T09:00:00Z`	`1983-04-24 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`1983-10-30T08:00:00Z`	`1983-10-30 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`1984-04-29T09:00:00Z`	`1984-04-29 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`1984-10-28T08:00:00Z`	`1984-10-28 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`1985-04-28T09:00:00Z`	`1985-04-28 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`1985-10-27T08:00:00Z`	`1985-10-27 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`1986-04-27T09:00:00Z`	`1986-04-27 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`1986-10-26T08:00:00Z`	`1986-10-26 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`1987-04-05T09:00:00Z`	`1987-04-05 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`1987-10-25T08:00:00Z`	`1987-10-25 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`1988-04-03T09:00:00Z`	`1988-04-03 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`1988-10-30T08:00:00Z`	`1988-10-30 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`1989-04-02T09:00:00Z`	`1989-04-02 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`1989-10-29T08:00:00Z`	`1989-10-29 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`1990-04-01T09:00:00Z`	`1990-04-01 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`1990-10-28T08:00:00Z`	`1990-10-28 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`1991-04-07T09:00:00Z`	`1991-04-07 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`1991-10-27T08:00:00Z`	`1991-10-27 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`1992-04-05T09:00:00Z`	`1992-04-05 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`1992-10-25T08:00:00Z`	`1992-10-25 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`1993-04-04T09:00:00Z`	`1993-04-04 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`1993-10-31T08:00:00Z`	`1993-10-31 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`1994-04-03T09:00:00Z`	`1994-04-03 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`1994-10-30T08:00:00Z`	`1994-10-30 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`1995-04-02T09:00:00Z`	`1995-04-02 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`1995-10-29T08:00:00Z`	`1995-10-29 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`1996-04-07T09:00:00Z`	`1996-04-07 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`1996-10-27T08:00:00Z`	`1996-10-27 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`1997-04-06T09:00:00Z`	`1997-04-06 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`1997-10-26T08:00:00Z`	`1997-10-26 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`1998-04-05T09:00:00Z`	`1998-04-05 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`1998-10-25T08:00:00Z`	`1998-10-25 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`1999-04-04T09:00:00Z`	`1999-04-04 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`1999-10-31T08:00:00Z`	`1999-10-31 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`2000-04-02T09:00:00Z`	`2000-04-02 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`2000-10-29T08:00:00Z`	`2000-10-29 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`2001-04-01T09:00:00Z`	`2001-04-01 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`2001-10-28T08:00:00Z`	`2001-10-28 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`2002-04-07T09:00:00Z`	`2002-04-07 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`2002-10-27T08:00:00Z`	`2002-10-27 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`2003-04-06T09:00:00Z`	`2003-04-06 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`2003-10-26T08:00:00Z`	`2003-10-26 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`2004-04-04T09:00:00Z`	`2004-04-04 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`2004-10-31T08:00:00Z`	`2004-10-31 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`2005-04-03T09:00:00Z`	`2005-04-03 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`2005-10-30T08:00:00Z`	`2005-10-30 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`2006-04-02T09:00:00Z`	`2006-04-02 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`2006-10-29T08:00:00Z`	`2006-10-29 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`2007-03-11T09:00:00Z`	`2007-03-11 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`2007-11-04T08:00:00Z`	`2007-11-04 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`2008-03-09T09:00:00Z`	`2008-03-09 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`2008-11-02T08:00:00Z`	`2008-11-02 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`2009-03-08T09:00:00Z`	`2009-03-08 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`2009-11-01T08:00:00Z`	`2009-11-01 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`2010-03-14T09:00:00Z`	`2010-03-14 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`2010-11-07T08:00:00Z`	`2010-11-07 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`2011-03-13T09:00:00Z`	`2011-03-13 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`2011-11-06T08:00:00Z`	`2011-11-06 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`2012-03-11T09:00:00Z`	`2012-03-11 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`2012-11-04T08:00:00Z`	`2012-11-04 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`2013-03-10T09:00:00Z`	`2013-03-10 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`2013-11-03T08:00:00Z`	`2013-11-03 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`2014-03-09T09:00:00Z`	`2014-03-09 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`2014-11-02T08:00:00Z`	`2014-11-02 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`2015-03-08T09:00:00Z`	`2015-03-08 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`2015-11-01T08:00:00Z`	`2015-11-01 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`2016-03-13T09:00:00Z`	`2016-03-13 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`2016-11-06T08:00:00Z`	`2016-11-06 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`2017-03-12T09:00:00Z`	`2017-03-12 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`2017-11-05T08:00:00Z`	`2017-11-05 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`2018-03-11T09:00:00Z`	`2018-03-11 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`2018-11-04T08:00:00Z`	`2018-11-04 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`2019-03-10T09:00:00Z`	`2019-03-10 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`2019-11-03T08:00:00Z`	`2019-11-03 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`2020-03-08T09:00:00Z`	`2020-03-08 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`2020-11-01T08:00:00Z`	`2020-11-01 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`2021-03-14T09:00:00Z`	`2021-03-14 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`2021-11-07T08:00:00Z`	`2021-11-07 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`2022-03-13T09:00:00Z`	`2022-03-13 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`2022-11-06T08:00:00Z`	`2022-11-06 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`2023-03-12T09:00:00Z`	`2023-03-12 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`2023-11-05T08:00:00Z`	`2023-11-05 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`2024-03-10T09:00:00Z`	`2024-03-10 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`2024-11-03T08:00:00Z`	`2024-11-03 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`2025-03-09T09:00:00Z`	`2025-03-09 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`2025-11-02T08:00:00Z`	`2025-11-02 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`2026-03-08T09:00:00Z`	`2026-03-08 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`2026-11-01T08:00:00Z`	`2026-11-01 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`2027-03-14T09:00:00Z`	`2027-03-14 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`2027-11-07T08:00:00Z`	`2027-11-07 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`2028-03-12T09:00:00Z`	`2028-03-12 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`2028-11-05T08:00:00Z`	`2028-11-05 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`2029-03-11T09:00:00Z`	`2029-03-11 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`2029-11-04T08:00:00Z`	`2029-11-04 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`2030-03-10T09:00:00Z`	`2030-03-10 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`2030-11-03T08:00:00Z`	`2030-11-03 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`2031-03-09T09:00:00Z`	`2031-03-09 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`2031-11-02T08:00:00Z`	`2031-11-02 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`2032-03-14T09:00:00Z`	`2032-03-14 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`2032-11-07T08:00:00Z`	`2032-11-07 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`2033-03-13T09:00:00Z`	`2033-03-13 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`2033-11-06T08:00:00Z`	`2033-11-06 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`2034-03-12T09:00:00Z`	`2034-03-12 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`2034-11-05T08:00:00Z`	`2034-11-05 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`2035-03-11T09:00:00Z`	`2035-03-11 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`2035-11-04T08:00:00Z`	`2035-11-04 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`2036-03-09T09:00:00Z`	`2036-03-09 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`2036-11-02T08:00:00Z`	`2036-11-02 01:00:00`	-06:00 → -07:00	`MST`	No	overlap
`2037-03-08T09:00:00Z`	`2037-03-08 03:00:00`	-07:00 → -06:00	`MDT`	Yes	gap
`2037-11-01T08:00:00Z`	`2037-11-01 01:00:00`	-06:00 → -07:00	`MST`	No	overlap

Notes from the Maintainers

Source: northamerica (Lines 829 to 848)

From Arthur David Olson (1988-02-13):
A writer from the Inter Tribal Council of Arizona, Inc.,
notes in private correspondence dated 1987-12-28 that "Presently, only the
Navajo Nation participates in the Daylight Saving Time policy, due to its
large size and location in three states."  (The "only" means that other
tribal nations don't use DST.)

From Paul Eggert (2013-08-26):
See America/Denver for a zone appropriate for the Navajo Nation.

Southern Idaho (Ada, Adams, Bannock, Bear Lake, Bingham, Blaine,
Boise, Bonneville, Butte, Camas, Canyon, Caribou, Cassia, Clark,
Custer, Elmore, Franklin, Fremont, Gem, Gooding, Jefferson, Jerome,
Lemhi, Lincoln, Madison, Minidoka, Oneida, Owyhee, Payette, Power,
Teton, Twin Falls, Valley, Washington counties, and the southern
quarter of Idaho county) and eastern Oregon (most of Malheur County)
switched four weeks late in 1974.

Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]

Attributed Statements:

Arthur David Olson (1988-02-13):

A writer from the Inter Tribal Council of Arizona, Inc., notes in private correspondence dated 1987-12-28 that "Presently, only the Navajo Nation participates in the Daylight Saving Time policy, due to its large size and location in three states." (The "only" means that other tribal nations don't use DST.)

Paul Eggert (2013-08-26):

See America/Denver for a zone appropriate for the Navajo Nation. Southern Idaho (Ada, Adams, Bannock, Bear Lake, Bingham, Blaine, Boise, Bonneville, Butte, Camas, Canyon, Caribou, Cassia, Clark, Custer, Elmore, Franklin, Fremont, Gem, Gooding, Jefferson, Jerome, Lemhi, Lincoln, Madison, Minidoka, Oneida, Owyhee, Payette, Power, Teton, Twin Falls, Valley, Washington counties, and the southern quarter of Idaho county) and eastern Oregon (most of Malheur County) switched four weeks late in 1974. Zone NAME STDOFF RULES FORMAT [UNTIL]

Years on Record

Methodology Note: The 1970 Rule

tzdb guarantees accuracy for timestamps from 1970 onwards. Transitions prior to 1970 represent best-effort historical reconstructions.