Public libraries are in a period of rapid change, and if you don’t believe it, visit Portland.

In the same week that the wraps started to come off the $7.3 million renovation of its downtown main facility came the news that budget constraints will likely cause the Portland Public Library to close three of its smallest branches.

The decision to close the satellite facilities in the Reiche, East End and Riverton school complexes, a longtime money-saving target for the library’s administration, was announced after the city budget called for a third straight year of flat funding for the library.

According to testimony at a recent budget committee hearing, there is little that can be done to save the branches. Library officials said even if the city increased its allocation, it would use the money for other purposes and not keep the branches open.

The library is figuring out where it fits in an age where a person can search all the periodicals in the world from his cell phone. The renovated downtown library offers an engaging public space in the heart of the city, with separate rooms for teens and young children, a coffee shop, a bank of computers, public meeting space, an art gallery and an auditorium, in addition to its collection of books, magazines, movies and recordings.

The proposal is to replace the branches with a mobile outreach program, which might help some patrons but will not be the same as a brick-and-mortar facility where someone can sit and read or use a computer. Neighborhood groups can protest, but the library is run by its trustees and not the city’s elected leadership.

In the future, the city should decide whether its relationship with the library — in which taxpayers provide most of the funding, but the trustees, who may not even be Portland residents, have control over how it is spent — makes sense. If the neighborhoods are not being served by the new system, neighborhood groups or other organizations could fill the void and host branch libraries or reading rooms with public support.

Until then, Portland can appreciate that even though it is losing its branch libraries, it will have an improved public building downtown, which comes on line at a time when most municipal services are being cut back.