Slowly but surely, a generational shift is afoot in MLS.

As the league approaches its third decade of existence, its ranks are gradually filling with players who grew up watching and supporting its teams as children, and dreamed of following in the footsteps of their heroes.

Long before he became an MLS Defender of the Year and US national teamer, Michael Parkhurst honed his savvy soccer IQ while sitting in the stands at New England Revolution games. USMNT star and former MetroStars (now New York Red Bulls) teenage prodigy Michael Bradley cut his teeth on the sidelines of D.C. United and Chicago Fire practices while his father Bob coached.

And before he was making saves for United's senior team, Bill Hamid was making the stands bounce at RFK Stadium with the Barra Brava supporters' group – and he has the pictures to prove it.

#TBT as a 14 year old watching DC United games in the Barra Brava Section. It was so fun making the… http://t.co/zQabYmfM5r — Bill Hamid (@BillHamid28) October 17, 2013

A native of Washington suburb Annandale, Va., Hamid grew up supporting the Black-and-Red long before he worked his way into the club's academy program and became its first-ever Homegrown signing in 2009. During his rookie season a year later, he set a league record as the youngest-ever goalkeeper to start an MLS match.

On Thursday, Hamid tweeted out a "Throwback Thursday" photo of his 14-year-old self watching a match intently along with the rest of “United's 12th Man” during D.C.'s run to their fourth MLS Cup championship in 2004, along with the proud hashtags #BeenAFan, #Since96, #ArealWashingtonian and #WhatDoesThisClubMeanToYou.

Several of his current and former teammates are in the same boat. Center back Ethan White served as a United ball boy while climbing through the ranks of the club's youth system. Onetime D.C. starlet and 2010 MLS Rookie of the Year Andy Najar wore the No. 14 jersey for United in tribute to his childhood favorite Ben Olsen, the former midfield dynamo who now coaches the Black-and-Red.

And similar stories can be found at other teams across the league.

What does this mean for the future of MLS? Will players who cheered for their clubs since childhood fight harder for the colors? Is the steady growth of the Homegrown initiative deepening teams' ties to their communities? Do fans cheer harder for local products?

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