League members in Maryland long have been active in the state, helping secure federal protection for the C&O Canal, clean up the Chesapeake Bay, and acquire state forest and park areas. The division, chartered by the League in 1945, also called for enactment of a 16-inch striped bass limit and a broader program of conservation education in public schools.

During the 1950s and early 1960s, the division worked to secure the 1961 federal designation of the C&O Canal as a national monument. The Save Our Streams Program, begun in 1969 in Maryland, expanded nationally in 1974. Since then, it has become one of the League's most successful and longest running conservation programs.

The Mid-Shore Chapter has operated recycling centers since the 1980s, with proceeds earmarked for environmental study scholarships.

During 1988 and 1989, the division led a campaign to pass the Maryland Non-tidal Wetlands Protection Act and held more than 20 regional workshops to train volunteers about ways to protect local wetlands.

In 1985, the Harford County Chapter began a conservation education program at a 243-acre marsh located along Otter Point Creek, a tributary to the Bush River. Due to the Chapter’s efforts, the area was added to the National Estuarine Research Reserve System in 1988.

In 1992, the division and other groups marked the end of a six-year fight to postpone construction of a waste incinerator in Dickerson, Md. During the late 1980s and early 1990s, the division worked for state protection of non-game and endangered species.