If public opinion changes and then public policy responds, this is dyn
amic representation. Public opinion is the global policy preference of
the American electorate. Policy is a diverse set of acts of elected a
nd unelected officials. Two mechanisms of policy responsiveness are (1
) elections change the government's political composition, which is th
en reflected in new policy and (2) policymakers calculate future (main
ly electoral) implications of current public views and act accordingly
(rational anticipation). We develop multiple indicators of policy act
ivity for the House, Senate, presidency, and Supreme Court, then model
policy liberalism as a joint function of the two mechanisms. For each
institution separately, and also in a global analysis of ''government
as a whole,'' we find that policy responds dynamically to public opin
ion change. This responsiveness varies by institution, both in level a
nd in mechanism, as would be expected from constitutional design.