Though New York City’s buses carry over two million passengers a day — more than the Long Island Rail Road, Metro-North, PATH and New Jersey Transit combined — they are often treated as an afterthought, even as they hemorrhage riders and strand the mostly low-income New Yorkers who depend on them, according to a report released on Monday by the city comptroller’s office.

The buses, which are operated by the Metropolitan Transportation Authority, travel at an average of under 8 miles per hour. That sluggish pace, combined with unreliable service, an aging fleet and routes that no longer match the commuting patterns of New Yorkers, has contributed to a steep drop in ridership over the past eight years: There were 100 million fewer passenger trips on the buses in 2016 than in 2008, the report says.

Much of the decline in ridership occurred in Manhattan, where the subways, though troubled in their own right, are at least readily available. But for many people in the other four boroughs, buses are the only public transportation available to carry them to work or school.

And when the buses run late, or barely run at all, those affected are often from low-income, minority or immigrant communities, the report says. The average personal income of bus commuters is $28,455, compared with $40,000 for subway commuters, the comptroller’s report says. More than half of bus commuters are foreign-born, and only 25 percent are white.