A regular expression that matches every US state or territory's name or postal abbreviation (I think)?

states_regexp.rb

expr = /^(
  a(
    [ksz] |
    (
      l(abam|ask)? |
      rizon
    )a |
    merican\ssamoa |
    r(kansas)?
  ) |
  c( t |
    a(lifornia)? |
    o(lorado|onnecticut)?
  ) |
  d( c |
    e(leware)? |
    istrict\sof\scolumbia
  ) |
  fl(orida)? |
  gu(am)? |
  h(awai)?i |
  i( n |
    d(aho)? |
    l(linois)? |
    (ndian|ow)?a
  ) |
  k(
    (ansa)?s |
    (entuc)?y |
  ) |
  m(
    [edsntp] |
    a(ine|ryland|ssachusetts)? |
    i(
      chigan |
      ss(issipp|our)i |
      nnesota
    )? |
    o(ntana)?
  ) |
  n(
    [vhjmycd] |
    e(
      (brask|vad)a |
      w\s(hampshire|jersey|mexico|york)
    )? |
    orthern\smariana\sislands
  ) |
  (nor|sou)th\s(carolin|dakot)a |
  o(
    h(io)? |
    k(lahoma)? |
    r(egon)
  ) |
  p( r |
    (ennsylvani)?a |
    uerto\srico
  ) |
  r(i|hode island) |
  s[cd] |
  t(
    [nx] |
    e(nnessee|xas)
  ) |
  u( m |
    nited\sstates\sminor\soutlying\sislands |
    t(ah)?
  )
  v(
    (ermon)?t |
    i(rgin\sislands)?
  ) |
  w(
    [avi] |
    (ashingto|isconsi)n |
    y(oming)?
  ) |
  ( v |
    l(ouisian)? |
    g(eorgi)? |
    (west\s)?virgini
  )a
)$/ix