Ever since we reported last year that L.A.'s growing transit system had shrinking ridership, folks have been scratching their heads.

The whole idea of expanding the region's light rail and subway lines was build it and they will come. And they will stay off the roads and alleviate traffic.

But traffic continued to be as bad as ever, and bus ridership was off 9.3 percent late last year compared with the same period in 2013. Even the Expo Line, the star of the local public transportation show, saw a 6 percent drop last year compared with its 2014 peak.

Officials blamed line repairs, service issues and undocumented immigrants for systemwide ridership declines. More than half a million folks without papers got California drivers licenses, many for the first time. Gas prices have been plummeting, too, making the near $2 one-way trip via public transit no bargain, especially if you have a Prius.

Oh, and that $1.75 bus fare went into effect in late 2014, just when ridership started to take a dive. Hmm.

But things are looking up.

For one thing, people seem pretty enthralled with the $1.5 billion, 6.6-mile Expo Line extension from Culver City to Santa Monica. It opened May 20.

The rides were free for the extension's first Friday and Saturday. Metro reports that boardings for May set a record: 1,155,343 compared with 796,877 in May 2015 and 828,866 in May 2014.

There were 39,237 weekday boardings in May on the Expo Line, a nearly one-third jump from the same time in 2015 and 2014, according to the transportation agency.

Total systemwide rail ridership for May (9,251,620) was greater than May 2015 (8,598,695) but slightly down from May 2014 (9,306,739).

Bus ridership (25,094,741 boardings in May) was down compared with the last two years (26,993,688 and 29,525,724). Rail and bus together (35,578,457) were down, too, compared with May in those two years: 36,882,597 and 40,242,833, respectively.

So you like to go to the beach. That's not a bad thing. Plus, gas prices usually head north for summer as vacation-triggered demand rises. We'll save a spot at the back of the train for you. Use it. Your taxes paid for it.