Rails Select Drop Down for States?

some helper file

def us_states
    [
      ['Alabama', 'AL'],
      ['Alaska', 'AK'],
      ['Arizona', 'AZ'],
      ['Arkansas', 'AR'],
      ['California', 'CA'],
      ['Colorado', 'CO'],
      ['Connecticut', 'CT'],
      ['Delaware', 'DE'],
      ['District of Columbia', 'DC'],
      ['Florida', 'FL'],
      ['Georgia', 'GA'],
      ['Hawaii', 'HI'],
      ['Idaho', 'ID'],
      ['Illinois', 'IL'],
      ['Indiana', 'IN'],
      ['Iowa', 'IA'],
      ['Kansas', 'KS'],
      ['Kentucky', 'KY'],
      ['Louisiana', 'LA'],
      ['Maine', 'ME'],
      ['Maryland', 'MD'],
      ['Massachusetts', 'MA'],
      ['Michigan', 'MI'],
      ['Minnesota', 'MN'],
      ['Mississippi', 'MS'],
      ['Missouri', 'MO'],
      ['Montana', 'MT'],
      ['Nebraska', 'NE'],
      ['Nevada', 'NV'],
      ['New Hampshire', 'NH'],
      ['New Jersey', 'NJ'],
      ['New Mexico', 'NM'],
      ['New York', 'NY'],
      ['North Carolina', 'NC'],
      ['North Dakota', 'ND'],
      ['Ohio', 'OH'],
      ['Oklahoma', 'OK'],
      ['Oregon', 'OR'],
      ['Pennsylvania', 'PA'],
      ['Puerto Rico', 'PR'],
      ['Rhode Island', 'RI'],
      ['South Carolina', 'SC'],
      ['South Dakota', 'SD'],
      ['Tennessee', 'TN'],
      ['Texas', 'TX'],
      ['Utah', 'UT'],
      ['Vermont', 'VT'],
      ['Virginia', 'VA'],
      ['Washington', 'WA'],
      ['West Virginia', 'WV'],
      ['Wisconsin', 'WI'],
      ['Wyoming', 'WY']
    ]
end

in some form

<%= select_tag :state, options_for_select(us_states) %>

Thanks Codeglot. In case anyone is wanting to display the 2-letter state abbreviation instead of the full name:

def us_states
  [
    ['AK', 'AK'],
    ['AL', 'AL'],
    ['AR', 'AR'],
    ['AZ', 'AZ'],
    ['CA', 'CA'],
    ['CO', 'CO'],
    ['CT', 'CT'],
    ['DC', 'DC'],
    ['DE', 'DE'],
    ['FL', 'FL'],
    ['GA', 'GA'],
    ['HI', 'HI'],
    ['IA', 'IA'],
    ['ID', 'ID'],
    ['IL', 'IL'],
    ['IN', 'IN'],
    ['KS', 'KS'],
    ['KY', 'KY'],
    ['LA', 'LA'],
    ['MA', 'MA'],
    ['MD', 'MD'],
    ['ME', 'ME'],
    ['MI', 'MI'],
    ['MN', 'MN'],
    ['MO', 'MO'],
    ['MS', 'MS'],
    ['MT', 'MT'],
    ['NC', 'NC'],
    ['ND', 'ND'],
    ['NE', 'NE'],
    ['NH', 'NH'],
    ['NJ', 'NJ'],
    ['NM', 'NM'],
    ['NV', 'NV'],
    ['NY', 'NY'],
    ['OH', 'OH'],
    ['OK', 'OK'],
    ['OR', 'OR'],
    ['PA', 'PA'],
    ['RI', 'RI'],
    ['SC', 'SC'],
    ['SD', 'SD'],
    ['TN', 'TN'],
    ['TX', 'TX'],
    ['UT', 'UT'],
    ['VA', 'VA'],
    ['VT', 'VT'],
    ['WA', 'WA'],
    ['WI', 'WI'],
    ['WV', 'WV'],
    ['WY', 'WY']
  ]
end

This is a more detailed walkthrough. I'm using Rails 4:

Under the helpers folder I created states_helper.rb

Inside states_helper.rb:

module StatesHelper

def us_states
  [
    ['Alabama', 'AL'],
    ['Alaska', 'AK'],
    ['Arizona', 'AZ'],
    ['Arkansas', 'AR'],
    ['California', 'CA'],
    ['Colorado', 'CO'],
    ['Connecticut', 'CT'],
    ['Delaware', 'DE'],
    ['District of Columbia', 'DC'],
    ['Florida', 'FL'],
    ['Georgia', 'GA'],
    ['Hawaii', 'HI'],
    ['Idaho', 'ID'],
    ['Illinois', 'IL'],
    ['Indiana', 'IN'],
    ['Iowa', 'IA'],
    ['Kansas', 'KS'],
    ['Kentucky', 'KY'],
    ['Louisiana', 'LA'],
    ['Maine', 'ME'],
    ['Maryland', 'MD'],
    ['Massachusetts', 'MA'],
    ['Michigan', 'MI'],
    ['Minnesota', 'MN'],
    ['Mississippi', 'MS'],
    ['Missouri', 'MO'],
    ['Montana', 'MT'],
    ['Nebraska', 'NE'],
    ['Nevada', 'NV'],
    ['New Hampshire', 'NH'],
    ['New Jersey', 'NJ'],
    ['New Mexico', 'NM'],
    ['New York', 'NY'],
    ['North Carolina', 'NC'],
    ['North Dakota', 'ND'],
    ['Ohio', 'OH'],
    ['Oklahoma', 'OK'],
    ['Oregon', 'OR'],
    ['Pennsylvania', 'PA'],
    ['Puerto Rico', 'PR'],
    ['Rhode Island', 'RI'],
    ['South Carolina', 'SC'],
    ['South Dakota', 'SD'],
    ['Tennessee', 'TN'],
    ['Texas', 'TX'],
    ['Utah', 'UT'],
    ['Vermont', 'VT'],
    ['Virginia', 'VA'],
    ['Washington', 'WA'],
    ['West Virginia', 'WV'],
    ['Wisconsin', 'WI'],
    ['Wyoming', 'WY']
  ]
end
end

Under config -> environments I put the following inside development.rb and production.rb

config.action_controller.include_all_helpers = true

Finally, inside my view I put (this is typed out in Slim HTML)

= form_for :order_submissions, url: order_url, html: { id: "order_form"} do |f|
fieldset
.form-group
  = f.select(:state, options_for_select(us_states, "CA"))

The "CA" pre-selects California in the dropdown menu on load.

NOTE: I did NOT use select_tag. Using it gave me an undefined method error for select_tag (select_tag is in the Ruby guides, how can it be undefined?) Using just select made it work.

For this I typically use the Carmen and Carmen-Rails gems.

https://github.com/jim/carmen

https://github.com/jim/carmen-rails

Since my projects are still all on Ruby 1.8, I have to use the specific ruby-18 branch, so I have the following in my Gemfile:

gem 'carmen', :git => 'git://github.com/jim/carmen.git', :tag => 'ruby-18'
gem 'carmen-rails', :git => 'git://github.com/jim/carmen-rails.git'

Then, to create the select tag for all US states in a form where you're editing the :state_code field of an :address model object...

subregion_select(:address, :state_code, Carmen::Country.coded('US'))