A line of impatient music fans slithered down the sidewalk of the North Park Observatory Thursday, March 16.

And impatience was understandable, as Portugal. The Man stopped by on its North American headline tour for a night of psychedelic riffs and audience sing-alongs.

A liveliness slowly built in the venue as opener HDBEENDOPE introduced the night, spewing an onslaught of gritty rap tracks over a turntable and live drums.

Strutting back and forth across the stage with undying energy throughout his set, the Brooklyn MC proved through sweat and rhymes to be a promising up-and-coming rap prospect.

He exited the stage after articulating his gratitude toward Portugal. The Man for bringing him on tour.

By now the spacious venue was filled with people.

The overhanging balcony was lined with camera phones and widening grins. Clamor in the form of whistles and shouts stirred from the ground-level audience pit.

After 30 minutes of collective anticipation, psychedelic collages splashed upon the backdrop as four outlined figures tiptoed onto the stage.

Kyle O’Quin assumed his position at the keyboard as Jason Sechrist took a seat behind the drums.

Zachary Carothers slung his bass guitar over his shoulder while lead singer John Gourley crept toward a microphone on the opposite side of the stage.

The crowd explodes. Wasting no time on igniting its set, the indie-rock eccentrics opened with “Church Mouth,” a drum-powered rock narrative dating back to their second studio album of the same name.

From there, momentum only snowballed as the highly-played single, “Creep in a T-Shirt” filled the room.

This oozed into the 2006 track, “Chicago,” where Gourley’s high-pitched vocals collided with the crowd’s as he crooned, “I can’t hear with these clouds in my ears.”

After just three songs the Portland-based rock outfit was already making one message quite clear to all in attendance: they were going to hop scotch all over their colorful discography, not favoring one particular piece of work over another.

After performing “Once Was One” and “Waves,” the venue dimmed as the visual backdrop projected a moon hovering above a silhouetted pyramid. With the chorus-catchy hit “All Your Light” erupting, the group perfected its rhythm, now fully stamping its powerhouse live presence.

What began as the normal version of the song quickly swerved off into a 12-minute improvised jam, even wiggling a cover of Ghostface Killah’s, “A Kilo,” into the mix.

From slow, creamy guitar riffs to hyperactive spurts of strumming, Portugal. The Man enjoyed altering the song tempo at a moment’s notice, keeping the audience involved and awake.

“They kept me guessing the entire set,” geology junior Mason Einbund said. “One second I would be head banging and the next I would be totally calm. Such as great time.”

As the finale of the drawn-out melody melted into a cover of the Beatles, “I Want You,” the smooth ad-libbed riffs only improved.

Carother’s humming bass plucks were tastefully complemented by O’Quin’s piano notes, high keys peppered in the background. Amidst the musical chaos, Gourley and O’Quin actually decided to trade instruments, the lead singer fingering the keys as O’Quin delivered a spastic flurry of guitar screeches.

When the amplifiers were hijacked by the band’s freshest single, “Feel it Still,” dance circles emerged throughout the crowd, a healthy dosage of brass horn flooding the venue.

While the band’s musical ability was palpable, other moments revealed the members’ good-humored personalities.

As Carothers encouraged the audience to clap in rhythm, a thundering crowd-chorus joined the band as they played a rendition of the song “Day Man” from the TV series “It’s Always Sunny in Philadelphia.”

Closing strong, the last five tunes included such indie classics as “So American,” “Modern Jesus,” and of course, “Purple Yellow Red and Blue.” The crowd’s reception was predictably deafening.

As trippy tie-dyed butterflies fluttered on the telescreen, the band bowed goodbye. Returning to the stage one last time after an uproar of encores, “Atomic Man” was screamed at full volume.

“Every time we come back it’s always bigger,” Carothers said before leaving the stage. “Always better. We thank you.”