The following directory is provided as a starting point.
When making contact with your States Department of Business / Labor
make sure to explain Your Trade and Location.
All contractors are treated differently within every State.
You can expect Plumbing, Electrical and any Health related contractor such as asbestos abatement or pesticides to go under strict guidelines both in the application and on going business process.
If you are an out of State Contractor there will be special requirements.
Alabama
http://www.genconbd.state.al.us/
Alaska
http://www.alaska.net/~achp/
Arizona
http://www.rc.state.az.us/
Arkansas
http://www.state.ar.us/clb/
California
http://www.cslb.ca.gov/
Colorado
http://www.dora.state.co.us/
General Contractors are not licensed by the State check for Local License requirements.
Connecticut
http://www.ct.gov/dcp/site/default.asp
Delaware
http://dedo.delaware.gov/
Florida
http://www.myflorida.com/dbpr/
Georgia
http://sos.georgia.gov/plb/
Hawaii
http://www.state.hi.us/dcca
Idaho
http://www.idaho.gov/
General Contractors are not licensed by the State check for Local License requirements.
Illinois
http://www.idfpr.com/
Indiana
http://www.in.gov/pla/
Iowa
http://www.iowa.gov/state/main/business.html
Kansas
General Contractors are not licensed by the State check for Local License requirements.
http://www.ksrevenue.org/
Kentucky
http://ohbc.ky.gov/
Louisiana
http://www.lslbc.state.la.us/
Maine
General Contractors are not licensed by the State check for Local License requirements.
http://www.maine.gov/
Maryland
General Contractors are not licensed by the State check for Local License requirements.
http://www.dllr.state.md.us/license/
Massachusetts
http://www.mass.gov/?pageID=eopshomepage&L=1&L0=Home&sid=Eeops
Michigan
http://www.michigan.gov/cis/
Minnesota
http://www.doli.state.mn.us/contractor.html
Mississippi
http://www.msboc.us/
Missouri
General Contractors are not licensed by the State check for Local License requirements.
http://www.mo.gov
Montana
http://erd.dli.mt.gov/
Nebraska
http://www.dol.state.ne.us/
Nevada
http://www.nvcontractorsboard.com/
New Hampshire
http://www.nh.gov/business/index.html
New Jersey
New Jersey is very strict and requires Licenses at an extreme micromanaged level. If you visit a property and do any type of work you can expect that some type of Specific License is required. That means everything from painters to plumbers.
http://www.state.nj.us/njbusiness/
New Mexico
http://www.rld.state.nm.us/CID/index.htm
New York
http://www.labor.state.ny.us
North Carolina
http://www.nclbgc.net/
North Dakota
http://www.nd.gov/sos/
Ohio
http://www.com.state.oh.us/dic/dicocilb.htm
Oklahoma
General Contractors are not licensed by the State check for Local License requirements.
http://www.oktax.state.ok.us/oktax/
Oregon
http://www.oregon.gov/CCB/index.shtml
Pennsylvania
http://www.dli.state.pa.us/landi/site/default.asp
Rhode Island
http://www.crb.ri.gov
South Carolina
http://www.llr.state.sc.us/POL/ResidentialBuilders/
South Dakota
Good luck using their website you will need it
http://www.state.sd.us
Tennessee
http://www.state.tn.us/commerce/boards/contractors/index.html
Texas
http://www.trcc.state.tx.us/
Utah
http://www.commerce.state.ut.us/
Vermont
http://vermont.gov/doing_business/business.html
Virginia
http://www.dpor.virginia.gov/dporweb/dpormainwelcome.cfm
Washington
This is another Micromanaged Licensed State like NJ and HI they have licenses for every single little thing you can think of. Good Luck to you if you want to be a contractor in Washington.
http://access.wa.gov/business/index.aspx
West Virginia
http://www.wvlabor.org/
Wisconsin
http://commerce.wi.gov/
Wyoming
http://wyoming.gov/business.asp
Washington DC
http://dcra.dc.gov/dcra/site/default.asp