The library's 23 branches and bookmobile services reach every incorporated city in the two counties, with the exception of Everett (which retains its own municipal system) and Woodway.

[12] Rural branches would rely on property taxes generated within the district, as well as donations from organizations and members of the community.

[14] Incorporated cities began voting to annex themselves into the Sno-Isle district in the late 1980s,[15] with promises of new libraries and potential cost savings over the contracted service.

[17] All Sno-Isle branches were closed in March 2020 due to the COVID-19 pandemic, but reopened with curbside pick-up service three months later.

[20] The Everett Public Library's board of trustees opposed the proposal, which would require voter approval.

[22] A permanent library for the Mariner neighborhood is planned to begin construction in 2026 as part of a mixed-use development.

[25] The Sno-Isle Libraries system is headquartered at an administration and processing center on the Tulalip Indian Reservation, west of Marysville.