A $1.5 million competition by the Knight Foundation for the best ideas to enliven St. Paul neighborhoods on the Green Line light-rail corridor was announced Thursday at the annual Great River Gathering in downtown St. Paul.

Applications for the Green Line Challenge will be accepted for one month starting June 24. That’s 10 days after the light-rail line linking downtown Minneapolis and downtown St. Paul is set to open.

“The new Green Line brings with it the potential to better connect people, places and ideas. We want to build on that energy and the work already underway,” Carol Coletta, Knight’s vice president of community and national initiatives, said in a statement.

Knight expects to award about $500,000 in grants for 15 to 30 projects this year, with additional awards in 2015 and 2016. The grants may range from $1,000 to $75,000. Any person, business or nonprofit can apply. More information: knightgreenlinechallenge.org.

The projects must occur in and benefit one of the St. Paul neighborhoods on the line: downtown, Frogtown/Thomas-Dale, Summit-University, Hamline Midway, Union Park and St. Anthony Park. They will be judged on their possible impact on the neighborhood, how close they are to the Green Line and whether they are doable.

The Knight Foundation belongs to the Central Corridor Funders Collaborative, a group of foundations working to prepare neighborhoods for the Green Line’s opening.