# MDY Date (slash-separated) Key: `datetime.date.mdy_slash` Month/Day/Year with slash separators. Standard US date format. Ambiguous with DMY format for days 1-12 — column-mode inference uses value distribution to disambiguate. Page: Format: `%m/%d/%Y` Samples: `01/15/2024`, `12/31/2019` ## Written by Each locale below writes this format with its CLDR date pattern at the styles named beside it. `es` (PA, PR) medium · `iu` short ## Background ### Origin In the United States, dates are traditionally written in month-day-year order, with neither increasing nor decreasing order of significance.[[1]](https://en.wikipedia.org/wiki/Date_and_time_notation_in_the_United_States) The month-day-year order is described as middle endian.[[1]](https://en.wikipedia.org/wiki/Date_and_time_notation_in_the_United_States) The traditional American all-numeric date follows the same month-day-year order, as in 01/21/2024.[[1]](https://en.wikipedia.org/wiki/Date_and_time_notation_in_the_United_States) The slash is the most commonly used separator in the American all-numeric date.[[1]](https://en.wikipedia.org/wiki/Date_and_time_notation_in_the_United_States) The hyphen and the period have also emerged as separators in the American all-numeric format, a change attributed to globalisation.[[1]](https://en.wikipedia.org/wiki/Date_and_time_notation_in_the_United_States) In the Unicode CLDR locale data, the medium date pattern for Spanish as used in Puerto Rico (es-PR) is MM/dd/y.[[2]](https://raw.githubusercontent.com/unicode-org/cldr-json/main/cldr-json/cldr-dates-full/main/es-PR/ca-gregorian.json) In the Unicode CLDR locale data, the medium date pattern for Spanish as used in Panama (es-PA) is MM/dd/y.[[3]](https://raw.githubusercontent.com/unicode-org/cldr-json/main/cldr-json/cldr-dates-full/main/es-PA/ca-gregorian.json) ### Use In SQL Server, CONVERT style 101 is labelled U.S. and produces MM/dd/yyyy.[[4]](https://learn.microsoft.com/en-us/sql/t-sql/functions/cast-and-convert-transact-sql?view=sql-server-ver17) The SQL Server documentation's example of CONVERT style 101 returns 08/23/2019.[[4]](https://learn.microsoft.com/en-us/sql/t-sql/functions/cast-and-convert-transact-sql?view=sql-server-ver17) In Python's strftime and strptime format codes, %m is the month as a zero-padded decimal number.[[5]](https://docs.python.org/3/library/datetime.html) In Python's strftime and strptime format codes, %d is the day of the month as a zero-padded decimal number.[[5]](https://docs.python.org/3/library/datetime.html) Python's documentation gives 08/16/1988 as the en\_US example of %x, the locale's appropriate date representation.[[5]](https://docs.python.org/3/library/datetime.html) American notation has influenced date notation in Canada, creating confusion in international commerce.[[1]](https://en.wikipedia.org/wiki/Date_and_time_notation_in_the_United_States) The Chicago Manual of Style discourages all-numeric dates other than the ISO 8601 year-month-day form, because they are not comprehensible to readers outside the United States.[[1]](https://en.wikipedia.org/wiki/Date_and_time_notation_in_the_United_States) Any value whose first two numbers are both 12 or under reads equally well as month-first or day-first, so one row cannot tell you which order a file uses. (Meridian's view) Look down the whole column for a first field above 12, which settles the file as day-first, or a second field above 12, which settles it as month-first, before you parse anything. (Meridian's view) When every value in a column is ambiguous, ask where the file came from and which convention its producer follows before choosing an order. (Meridian's view) ### Where you'll meet it The U.S. Department of the Treasury's Daily Treasury Par Yield Curve Rates table writes its dates as month/day/year with slashes, such as 12/31/2024.[[6]](https://home.treasury.gov/resource-center/data-chart-center/interest-rates/TextView?type=daily_treasury_yield_curve&field_tdr_date_value=2024) ## Sources 1. [Date and time notation in the United States](https://en.wikipedia.org/wiki/Date_and_time_notation_in_the_United_States) — secondary source 2. [ca-gregorian.json (es-PR)](https://raw.githubusercontent.com/unicode-org/cldr-json/main/cldr-json/cldr-dates-full/main/es-PR/ca-gregorian.json) — documentation 3. [ca-gregorian.json (es-PA)](https://raw.githubusercontent.com/unicode-org/cldr-json/main/cldr-json/cldr-dates-full/main/es-PA/ca-gregorian.json) — documentation 4. [CAST and CONVERT (Transact-SQL) - SQL Server \| Microsoft Learn](https://learn.microsoft.com/en-us/sql/t-sql/functions/cast-and-convert-transact-sql?view=sql-server-ver17) — documentation 5. [datetime — Basic date and time types](https://docs.python.org/3/library/datetime.html) — documentation 6. [Daily Treasury Rates \| U.S. Department of the Treasury](https://home.treasury.gov/resource-center/data-chart-center/interest-rates/TextView?type=daily_treasury_yield_curve&field_tdr_date_value=2024) — dataset