United States
USPTO Main web page: http://www.uspto.gov/
Issued Patents:
Database to Search all Existing Patents, 1790-1975:
Patents from 1790 through 1975 are searchable only by Issue Date, Patent Number, and Current US Classification. When searching for specific numbers in the Patent Number field, patent numbers must be seven characters in length, excluding commas, which are optional.
http://patft.uspto.gov/netahtml/PTO/search-bool.html
USPTO Patent Databases, which include PAIR and several other databases of value, which can be used to search US patents back to the very beginning in 1790:
http://www.uspto.gov/patents/process/search/index.jsp
Google Patent Search - Advanced
http://www.google.com/advanced_patent_search
Patent Applications:
USPTO PAIR Database, where patents can be searched by Patent application Number:
http://www.uspto.gov/patents/process/status/private_pair/index.jsp#
USPTO Patent Application Publication Data Products:
These "data products" they offer are only for patent applications made from 2001 to the present, and not prior to 2001.
http://www.uspto.gov/products/catalog/patent_applications.jsp#heading-1
USPTO Patent Application Full-Text and Image Database (2001-present):
You can search for Full-Text and Image versions of patent applications, and customize searches on all fields of a patent application in this database, including applicant’s name, patent title, applicant city, application serial number, etc. But you can only search back to 2001.
http://appft.uspto.gov/netahtml/PTO/search-adv.html
Patent Application Statistics (number of PAs), by year vs issued Patents (1790-present):
http://www.uspto.gov/web/offices/ac/ido/oeip/taf/h_counts.htm
Classification System:
USPTO Patent Classification System Database, alphabetical:
http://www.uspto.gov/web/patents/classification/uspcindex/indextouspc.htm
USPTO Patent Classification System Database, Numerical:
http://www.uspto.gov/web/patents/classification/selectnumwithtitle.htm
The great thing about this database is that you can instantly link to all the patents that have been granted in these very detailed subgroups, by just clicking on the "P" at the left side of every classification number.
Environmentally Sound Technologies Group of USPTO classifications, with correspnding WIPO "Green Technology" classifications:
http://www.uspto.gov/web/patents/classification/international/est_concordance.htm
Secrecy Orders:
Secrecy Orders, US: USPTO Secrecy Orders -- Statistics for Fiscal Years (FY), 1988-2012:
https://www.fas.org/sgp/othergov/invention/stats.pdf
Secrecy Orders, US: Large list of website links related to USPTO Secrecy Orders provided by the Project on Government Secrecy, sponsored by the Federation of American Scientists (FAS):
http://www.fas.org/sgp/othergov/invention/
NARA Offices and People Administering Patent Records:
US National Archives Patent Application Records (Group 241.3):
http://www.archives.gov/research/guide-fed-records/groups/241.html
USPTO Public Search facility, 600 Dulany, Alexandria, VA: phone: 571-272-3275
http://www.uspto.gov/products/library/search/index.jsp
USPTO Scientific and Technical Information Center, 400 Dulany St., Alexandria, VA (This is actually the main library): 571-272-2520; 571-272-3547;
http://www.uspto.gov/patents/process/search/sticlibinfo.jsp
USPTO and Other Patent and Patent Office Historians: (search WorldCat for books on patent history, and SCOPUS or WOK/WOS for articles)
Canada (began issuing patents in 1869)
Canadian Patent Office Contact Information:
Email address: cipo.contact@ic.gc.ca
Toll-free from anywhere in Canada and the U.S. to our Client Service Centre
1-866-997-1936; International calls only: 819-934-0544
Hours: 8:30 a.m. to 5:00 p.m. (EST) Monday to Friday (except Statutory Holidays
Issued Patents:
This is a very easy and useful patent search engine where yo can search by key word, inventor name, title word, and many other fields.
http://brevets-patents.ic.gc.ca/opic-cipo/cpd/eng/search/advanced.html
Worldwide Patent Offices and Information, Outside the United States
WIPO Patentscope Database of 35 million patent documents:
http://patentscope.wipo.int/search/en/search.jsf
Worldwide Patent Offices for each country and territory: click here
World Intellectrual Property Organization (WIPO) website:
http://www.wipo.int/portal/en/index.html
This website lists some, but not all, patent offices around the world.
WIPO International Patent Classification (IPC) Home Page:
http://www.wipo.int/classifications/ipc/en/
You can browse by categories, etc, plus it has FAQs, etc.
WIPO International Patent Classification (IPC) "Green Inventory"
http://www.wipo.int/classifications/ipc/en/est/
This is a group of IPC classications that relate to Green technologies, but as the site says, it is not exhaustive, and you should check under the main classifications.