In the United States, most roads originate from TIGER from the Census Bureau. Geographic names were initially sourced from Geographic Names Information System, and some areas contain water features from the National Hydrography Dataset. In the UK, some Ordnance Survey OpenData is imported. In Canada Natural Resources Canada's CanVec vector data and GeoBase provide landcover and streets. Out-of-copyright maps can be good sources of information about features that do not change frequently. Copyright periods vary, but in the UK Crown copyright expires after 50 years and hence Ordnance Survey maps until the 1960s can legally be used. A complete set of UK 1 inch/mile maps from the late 1940s and early 1950s has been collected, scanned, and is available online as a resource for contributors. Contributors The project has a geographically diverse user-base, due to emphasis of local knowledge and "on-the-ground" situation in the process of data collection. Many early contributors were cyclists who survey with and for bicyclists, charting cycleroutes and navigable trails. Others are GIS professionals who contribute data with an extension for ArcGIS. Contributors are predominately men, with only 3–5% being women. By August 2008, shortly after the second The State of the Map conference was held, there were over 50,000 registered contributors; by March 2009, there were 100,000 and by the end of 2009 the figure was nearly 200,000. In April 2012, OpenStreetMap cleared 600,000 registered contributors. On 6 January 2013, OpenStreetMap reached one million registered users. Around 30% of users have contributed at least one point to the OpenStreetMap database. Since 2007, the OpenStreetMap community has held an annual, international conference called State of the Map. There are also various national, regional and continental SotM conferences, such as SotM U.S., SotM Baltics, SotM Asia & SotM Africa. Commercial contributors Some OpenStreetMap data is supplied by companies that choose to freely license either actual street data or satellite imagery sources from which OpenStreetMap contributors can trace roads and features. Notably, Automotive Navigation Data provided a complete road data set for Netherlands and details of trunk roads in China and India. In December 2006, Yahoo! confirmed that OpenStreetMap was able to make use of their vertical aerial imagery and this photography was available within the editing software as an overlay. Contributors could create their vector based maps as a derived work, released with a free and open licence, until the shutdown of the Yahoo! Maps API on