California lawmaker Rep. Janice Hahn, who represents the California district that includes the Port of Los Angeles, said Tuesday that she will not run for re-election next year and will instead run for an open seat on the Los Angeles County Board of Supervisors.

Hahn, a 62-year-old Democrat, was a strong advocate for greater port and overall transport funding. She introduced legislation last July that would channel 5 percent of all import duties to finance a trust fund dedicated for freight-only mobility projects. The National Freight Network Trust Fund Act of 2014 would have directed duties into a separate fund that would pay for road improvements within a federally designated "national freight network," as well as for rail lines that connect the network to the country's ports of entry.

Hahn's legislation was believed to be the first to ever consider import duties as a funding mechanism for freight transportation projects.

At the time, Rep. Hahn said her bill would ensure that improvements to the nation's freight system would be paid for by those who stood to benefit the most from it. "The taxes and fees our nation collects should be spent on the purpose they were collected for, much like the Harbor Maintenance Tax is spent to improve ports," she said in a statement back then.

Hahn's 44th Congressional District does not include the Port of Long Beach, which sits adjacent to the Port of Los Angeles.