CAPE ELIZABETH — The lighthouse started gaining on us in the fifth mile of the TD Beach to Beacon 10K road race Saturday, and for a while it seemed the perfect way to reach the finish line and end our journey.

Not a real lighthouse: One constructed from lumber, fabric and wheels, and pushed from within by Dave Jackiewiecz, whose other running costumes include a moose and an oversized beer bottle.

My firstborn, Lily, turned 18 this spring. She leaves for college later this month. The first place she called home was a two-bedroom apartment inside the keepers’ quarters at Portland Head Light.

The women who worked in the adjacent gift shop and first-floor museum fawned over our baby and dubbed her Lily of the Lighthouse. I rocked her to sleep overlooking the pebbly beach where the “Annie C. Maguire” wrecked in 1886. She liked movement.

Her first time doing the Beach to Beacon came in the inaugural year of 1998. The next year, when Lily was 2, we did it again.

Until Saturday, that was the last time I ran Beach to Beacon.

One reason is Lily grew too big for a baby jogger. The race did, too. The roads, and particularly the area inside Fort Williams Park, became too crowded for parent-propelled buggies.

Another reason was I began covering the race and soon became the Press Herald’s B2B scribe, the guy who could remember the two i’s in Kristin Barry and recognize the rising high school runners. It became a proprietary thing. The race, after all, ends on what used to be my front yard. It runs through my town.

And then, way too quickly, this spring Lily was marching through Fort Williams to “Pomp and Circumstance” on a sunny June Sunday. As she accepted her diploma, her sentimental dad kept his emotions in check. But as mortarboards sailed skyward and music blared, however, I choked up.

Getting to the start of the B2B takes commitment; we hitched a ride with a kind neighbor whose daughter was running. Soon we were navigating through the mass of humanity, porta-potties and temporary fencing. The wheelchair athletes had a special bus, driven by none other than Nasty Nate, the friendly guy whose recent winters included helping Lily lug her bulky goalie equipment to hockey games and practices. She also saw her friend Christina Kouros, who went on to win the women’s wheelchair division for a third straight year.

Sixteen years ago I controlled the pace. This time it was Lily’s turn. We settled ourselves in among the 10-minute milers along Bowery Beach Road, treading on the softer shoulders as much as possible.

We saw friends. We high-fived small children. We encountered Lily’s longtime volunteer softball coach and her second-grade teacher, as enthusiastic as if Lily had written a clever squiggle-prompt story.

Approaching Old Ocean House Road, I welcomed the return of the Shower of Power, and ducked beneath its welcoming spray. From the bay of the press truck, you miss such homey touches. Another nice touch: the oddly inspiring rhythm of a wooden spoon thumping hand-held saucepan.

We talked tangents – diagonal lines touching the inside of curves where the road bends – as if shaving fractions from our time actually mattered. We caught and passed the Cape Elizabeth High football team, among them Lily’s twin brothers. The tie-dyed girls’ soccer team proceeded to pass us. We heeded “Touch for Power” signs held by wide-eyed kids.

At two early water stations, I briefly lost track of Lily as we tried to drink and glide and not collide. A guy wearing earbuds and singing loudly (and off-key) led us to wonder if one of her brothers might do something similarly embarrassing. Upon turning onto Shore Road I stopped to embrace a friend who always Rollerblades from Portland to the traffic island at the Route 77 intersection.

This was more parade than race. Sort of like parenthood, a journey endless and eternal.

The sparkling waters of Pond Cove broke my reverie. The end was near and made me wonder if our remaining time together would prove poignant.

When the lighthouse guy approached us from behind, a fitting conclusion to our story emerged: Lily of the Lighthouse finishes alongside the beacon. Sail on ye stately ships, and all that Longfellow poetry.

Naturally we couldn’t keep up. Life so rarely delivers perfect endings.

We navigated the winding hills approaching Fort Williams and suddenly were making the turn (wide left, remembering the tangents) through the Old Gate in front of a much thicker crowd of spectators that included, we knew but never saw, mom and the family dog.

And that’s when the realization hit. My daughter had climbed to the edge of the nest and was about to fly.

Paternal tears never materialized, however, because our competitive instincts kicked in. Lily still had plenty in her tank and started passing runners, weaving her way through the last quarter-mile.

Not wanting to lose her now, I hustled to keep up and before I knew it we were across the line, clasping a congratulatory hand from Maine’s most famous Olympian.

We hadn’t caught the mobile lighthouse after all but instead faced the familiar landmark from our old digs. We finished where we started 18 years ago, a father beaming with pride, trailing his daughter by a stride.