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American style month/day/year parsing for ruby 1.9



ruby-american_date exists to make ruby 1.9+ parse american-style month/day/year dates correctly, with behavior matching ruby 1.8.7. It can also be used on earlier ruby version, but it is basically a noop there.

As far as I know, there isn't a gem that already handles this. You can find many snippets on the web that partially solve the issue, but most won't be compatible with ruby 1.9.3, because Date.parse and DateTime.parse no longer call Date._parse directly on 1.9.3. Also most don't handle cases where an american date format is used in addition to a time format.

Note that this gem only handles / separated dates. It does not handle - or . separated dates. This is by design, for compatibility with ruby 1.8.7.


The general idea is fairly simple. We look for a month/day/year substring in the input string, and if we find it, we transform it into a year-month-day ISO format string before passing it to the standard date parsing methods. This is probably the least invasive way that works correctly on both the pure-ruby date parser (<1.9.3) and the C extension date parser (>=1.9.3).

Tested ruby versions

  • ruby 1.8.6, 1.8.7, 1.9.2, 1.9.3, 2.0.0, 2.1.0

  • rubinius 1.2.4, 2.2.6

  • jruby 1.6.5, 1.7.9 (both –1.8 and –1.9 modes)


ruby-american_date is distributed as a gem, and can be installed with:

gem install american_date


ruby-american_date is hosted on GitHub:


ruby-american_date uses GitHub Issues for issue tracking:


Jeremy Evans <>

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