A recent economic analysis indicates that a completed downtown area including the Stateline Loop Road proposal could increase annual retail sales increase of $16-$25 million, the Tahoe Transportation District announced Thursday.Under the proposal, downtown Stateline would include wider sidewalks, bike lanes, special bus lanes, transit stops, crossing opportunities, median islands and pedestrian signals. The project would support future development, from which the potential exists for more than a billion dollars in private construction activity, numerous short and long-term employment prospects as well as other recreational, environmental and community benefits, according to the analysis.Economic & Planning Systems, Inc., a Sacramento-based land …