A lot of US government information is freely available and searchable on the web. Using Google is pretty effective using the site limiter with your term. Just type, for example:
biosurveillance site:.gov
This will find any url ending in .gov with biosurveillance in the text.
.gov is used by some cities, counties, states and federal government entities use: there are, or course, other urls that may be relevant, such as .tx.us or .org or .mil. Then just modify the search for these endings.
This type of search can also be used to search the longer url:
Defense Department info is site:.defense.gov or site:.dod.gov
French government documents can be found with site:.gouv.fr while Spanish government documents are site:.gob.es
The convention is not universal but it can help locate and narrow information down government information. State government sites may have various url syntaxes that need to be taken into account:
California has site:.ca.gov
Texas mainly uses site:.tx.us
Florida uses site:.fl.us; however the Governor's site is site:.flgov.com and the various agencies have different url roots.
This search box will search the top 10 Energy and Resource Policy Web Sites as identified by the 2014 Global Go To Think Tank Report (from Penn).
