Transit ridership is on the wrong track across America. Yet until 2016, the San Francisco Bay Area appeared immune to the ridership declines plaguing most other cities. However, in 2017, Bay Area ridership began to fall, both regionwide and on almost all major transit operators. But this decline has not occurred uniformly. Thus, to help explain why transit ridership has changed, this report elucidates how, where, and when it has changed across the nine-county Metropolitan Transportation Commission region in the past decade. To answer these questions, I analyze ridership data for the region as a whole and for three of its largest operators in depth. Following this, I conduct a multivariate statistical analysis that simultaneously considers the various factors that have influenced ridership on Bay Area Rapid Transit (BART).While the landscape of transit use in Northern California is varied and shifting, I find and detail three significant trends. First, while the Bay Area had appeared to have stronger ridership than much of the rest of the country until recently, gains at major Bay Area transit agencies masked longer-term declines in the rest of the region. Second, the region’s largest operators are suffering from severe and deepening peaking problems: ridership during off-peak periods and in off-peak directions has cratered, while ridership at peak periods and in peak directions remains steady. Finally, I find that jobs, and particularly concentrated employment, explain far more of variation in ridership than any other determinant analyzed, including factors like service provided. Policymakers must therefore make the difficult decision of whether to channel resources towards the most crowded trip types, to alleviate crowding and double down on their strongest market, or towards slumping trips types, to shore up the weakest parts of the transit network despite their limited control over them.