2008-2013: The Early 2010s
*2008 is the transition year from the Late '00s. (Late 2006 - 2008)
*The first culturally early 2010s school year is 2008-09, although there are still many 2000s influences and it is transitional.
*Obama is elected in November 2008 and inaugurated in January 2009.
*The first "purely" early 2010s school year is the 2009-10 school year.
*2009 is when the sound of music that would dominate until about 2011/12 started gaining spotlight.
*The early 2010s peaked during the 2011-12 school year.
*The last culturally early 2010s school year is 2012-13.

2013-2016: The Core 2010s
*The first culturally core 2010s school year is 2013-14.
*GTA V is released, which would continue being updated throughout the rest of the decade and even all the way up to 2020 and beyond.
*Breaking Bad, the most popular show of the early '10s, ends in 2013.
*Blockbuster starts closing its doors in late 2013 and early 2014.
*The Ebola Outbreak and Ferguson Unrest happen in 2014.
*The core 2010s peaked during the 2014-15 school year.
*Trump announces that he's running for president in 2015.
*The last culturally core 2010s school year is 2015-16.

2016-2020: The Late 2010s
*In 2016, even before Trump was elected, the atmosphere changed from 2015 and everything seemed to get more edgy.
*The first culturally late 2010s school year is 2016-17.
*Trump wins the presidential election in November 2016 and is inaugurated in January 2017.
*The late 2010s peaked during the 2017-18 school year.
*The last culturally late 2010s school year is 2019-20, before they closed down in March.
*I view 2020 as culturally a very transitional year. The aftermath of all of the events of this year, plus the upcoming election and inauguration in January 2021, I think will give Late 2020 and 2021 a different feeling that will probably carry on until about 2023.

I'll go by U.S school years.


Cultural transition from late 2000's to early 2010's:

2008-2009


Cultural early 2010's:

2009-2010

2010-2011

2011-2012

Defined by: Obama's first term, electropop, Facebook, Lady Gaga, Katy Perry.


Cultural transition from early 2010's to mid-2010's:

2012-2013


Cultural mid-2010's:

2013-2014

2014-2015

2015-2016

Defined by: Obama's second term, Vine, a rise in SJW, legalization of gay marriage, Musical.ly, EDM


Cultural transition from mid-2010's to late 2010's:

2016-2017


Cultural late 2010's:

2016-2017

2017-2018

2018-2019

Defined by: Trump, Fortnite, Vaping, Parkland, March For Our Lives, rise in alt-right, TikTok


Cultural transition from late 2010's to early 2020's:

2019-2020

I still see the 2008-2009 school year as a solidly late '00s school year, by the simple fact that Myspace was still the most popular social media platform for teenagers, although Facebook was getting up there in popularity. By 2009-2010, Facebook had dethroned Myspace, so I'll grant that school year as a quasi-early '10s year.

*I've done a thread like this before although it was very inaccurate and I will provide an updated explanation later*

---Earliest Influences---
Fall 2006-Summer 2009: The late 2000s with vague Early 2010s introductions or influences that lingered on like the iPhone, 7th Gen consoles, HDTV, Teenybopper Disney, Electropop, etc.

---The Peripheral Early 2010s---
Fall 2009-Spring 2011: Transition from the Late 2000s to the Early 2010s

Spring 2011-Summer 2012: Quintessential Early 2010s period/'Electropop Era' Part 2

Fall 2012-Summer 2013: Transition from the Early 2010s to the Core 2010s

---The Core 2010s---
Fall 2013-Spring 2015: First Third of the Core 2010s, also known as the First Half of Mid 2010s

Summer 2015-Winter 2016/17: Quintessential Core 2010s Period

Winter 2016/17-Winter 2018/19: Late Core 2010s; The Modified Mid 2010s period with Pure Late 2010s influences creeping in

---The Peripheral Late 2010s---
Spring 2019-March 11th, 2020: Pure Late 2010s Period

March 11th, 2020: Coronavirus era

*Ill give a more in depth answer for this one later

I still see the 2008-2009 school year as a solidly late '00s school year, by the simple fact that Myspace was still the most popular social media platform for teenagers, although Facebook was getting up there in popularity. By 2009-2010, Facebook had dethroned Myspace, so I'll grant that school year as a quasi-early '10s year.

Honestly, with the 2008-2009 school year, I really feel like that was when 2000’s culture was dying and early 2010’s culture was starting to become big. You had the election of Obama, Facebook, Lady Gaga, and electropop songs like “Boom Boom Pow” that would sound out of place in even 2007. That school year IMO leans slightly early 2010’s culturally, especially the second half. It’s crazy how different 2007 and 2009 are despite being only two years apart.

Electropop era/Early 2010s

2008-2009: Dying 2000s culture making way to the early 2010s era. A lot of changes were happening throughout this school year.
2009-2010: Early 2010s overtook the 2000s but still has this underdeveloped feeling. There were still a visible amount trends from the 2000s.
2010-2011: The early 2010s felt almost complete with barely any 2000s carryovers left. The earliest core trends began to pop out here.
2011-2012: The peak of the era where there are no 2000s trends left. Core 2010s trends keep on appearing.
2012-2013: The decline of the era but it was slow, blurry, and gradual with no clear ending.

Vine-era/Core 2010s

2013-2014: The true 2010s have been established but carryovers from the last era were still remaining.
2014-2015: The 2010s are skyrocketing toward it's peak with barely any early 2010s leftovers.
2015-2016: Honestly the peak of the core 2010s, there are no more leftover trends from the early 2010s.
2016-2017: Transitioning to a new era for obvious reasons but still has this strong core atmosphere.

Fortnite-era/Late 2010s

2017-2018: Arguably the true start of the new era, but there are a lot of core elements lingering here.
2018-2019: Mostly late 2010s with barely any core 2010s trends.
2019-2020: Completely late 2010s with no core trends. From what I've witnessed, this could have the earliest trends for the early 2020s.

Electropop era/Early 2010s

2008-2009: Dying 2000s culture making way to the early 2010s era. A lot of changes were happening throughout this school year.
2009-2010: Early 2010s overtook the 2000s but still has this underdeveloped feeling. There were still a visible amount trends from the 2000s.
2010-2011: The early 2010s felt almost complete with barely any 2000s carryovers left. The earliest core trends began to pop out here.
2011-2012: The peak of the era where there are no 2000s trends left. Core 2010s trends keep on appearing.
2012-2013: The decline of the era but it was slow, blurry, and gradual with no clear ending.

Core 2010s

2013-2014: The true 2010s have been established but carryovers from the last era were still remaining.
2014-2015: The 2010s are skyrocketing toward it's peak with barely any early 2010s leftovers.
2015-2016: Honestly the peak of the core 2010s, there are no more leftover trends from the early 2010s.
2016-2017: Transitioning to a new era for obvious reasons but still has this strong core atmosphere.

Late 2010s

2017-2018: Arguably the true start of the new era, but there are a lot of core elements lingering here.
2018-2019: Mostly late 2010s with barely any core 2010s trends.
2019-2020: Completely late 2010s with no core trends. From what I've witnessed, this could have the earliest trends for the early 2020s.


I guess you can argue tik tok celebs(ugh lol) will be a 2020s trend

I still see the 2008-2009 school year as a solidly late '00s school year, by the simple fact that Myspace was still the most popular social media platform for teenagers, although Facebook was getting up there in popularity. By 2009-2010, Facebook had dethroned Myspace, so I'll grant that school year as a quasi-early '10s year.

Agreed.