Starting in the 1970s when San Franciscans began moving to the suburbs, SI’s demographics began changing, with more and more students coming from Marin and San Mateo Counties. SI struggled to find a way to afford a bus service, but each time it ran the numbers, the program proved too costly. Then, in 1984, the Youth Activities Department of the Catholic Youth Organization called SI with the offer of an affordable chartered bus service. The school subsidized the service, charging students $3 per day for round-trip service and $2 for one-way travel. On August 23, 1984, one bus left the parking lot at the Hillsdale Shopping Center in San Mateo and another left Terra Linda to pick up a total of 60 students on their way to SI, and those buses have continued making their runs for the past 20 years.
The bus service helped SI respond to its growing popularity among students from outside San Francisco. As home prices in San Francisco rose in the 1980s, many alumni moved to the suburbs but still wanted their children to attend SI. In 1988, for instance, 225 freshmen came to SI from San Francisco schools, while only 150 city students entered in 2004. The number of freshmen between 1988 and 2004 coming to SI from Marin County rose from 16 to 59, with similar increases for San Mateo County (66 to 126) and the East Bay (4 to 14) over that same time period.