New data from CALSTART’s Zeroing in on ZEBs market update shows transit agencies across the country increasing orders for battery-electric and hydrogen fuel cell buses as part of broader fleet modernization and emissions reduction strategies.
As of July 2025, the national pipeline includes 8,116 full-size zero-emission buses that are funded, ordered, delivered, or already operating. That figure represents a 16% increase compared with July 2024, despite ongoing procurement challenges and long manufacturing lead times.
California remains the largest market for zero-emission buses, but adoption is becoming more geographically diverse as transit agencies across the country begin integrating the technology into long-term fleet planning.
According to the report, California currently has 1,933 battery-electric buses and 690 hydrogen fuel cell buses either deployed or in the procurement pipeline. Several other states are also building sizable fleets.
New York ranks second nationally with 829 zero-emission buses, followed by Washington with 521. Adoption is also growing in the Southeast, with Florida reaching 519 buses, while Massachusetts has 292 vehicles in its pipeline.
Year-over-year growth has been particularly strong in several Midwestern and Western states, including Indiana, Wisconsin, Illinois, Washington, and California. The broader geographic spread suggests zero-emission buses are increasingly becoming part of mainstream fleet planning rather than limited pilot deployments.
Battery-electric buses continue to represent the majority of the zero-emission market. Nationwide, 7,261 battery-electric buses have been funded, ordered, delivered, or deployed, reflecting a 13% increase year over year.
Transit agencies cite improvements in battery technology, expanding charging infrastructure, and the relative maturity of the platform as key factors supporting continued growth.
Hydrogen fuel cell buses remain a smaller segment of the market but are expanding more rapidly. The report shows 855 fuel cell buses nationwide, marking a 49% increase during the latest reporting period.
California continues to lead hydrogen deployment, though other states are beginning to establish smaller fleets. Nevada currently operates 52 fuel cell buses, while New York has 15 and both Illinois and Ohio have 14 each.
Many transit agencies are evaluating hydrogen as a complementary option for routes with longer distances, heavier duty cycles, or operational constraints that may limit charging opportunities.
Federal funding programs remain a major driver of adoption. Grants from the Federal Transit Administration — including the Low or No Emission (Low-No) Program and the Grants for Buses and Bus Facilities Program created under the Infrastructure Investment and Jobs Act — have helped transit agencies finance both vehicles and charging infrastructure.
However, industry stakeholders continue to point to several structural challenges that could affect deployment timelines. Supply chain disruptions, limited domestic manufacturing capacity, and extended vehicle lead times remain persistent issues.
Even so, the latest data indicates that zero-emission buses are moving beyond early demonstration projects toward broader national deployment. With more than 1,000 additional vehicles added to the pipeline during the latest reporting period, transit agencies across the United States are gradually scaling the transition to zero-emission fleets.
