A full and growing list of events planned nationwide is available here.
The massacre is the deadliest mass shooting in modern U.S. history. The primary suspect, Omar Mateen, reportedly claimed ties to the Islamic State group before carrying out the attacks, for which the extremist group has since taken responsibility.
At the site of the ISIS-coordinated attack that killed 130 people in November, some 100 people assembled Sunday evening for what the Associated Press called a "spontaneous vigil" on Paris' Place Igor Stravinsky.
The ongoing candlelight vigil at the Washington Monument is one of many gatherings scheduled. Another took place outside the White House.
Mourners came together at Ten Atlanta, a local gay bar in Midtown.
A candlelight vigil brought hundreds Sunday evening to Boston's Copley Square.
At a vigil, a woman recited the Surah al Fatihah from the Quran, the Muslim holy book's preface that asks Allah's help in living righteously.
"Guide us on the straight path, the path of those who have received your grace," goes the verse. "Not the path of those who have brought down wrath, nor of those who wander astray."
In Ottawa, residents held a vigil where the known names of those lost in the "abhorrent acts of violence" perpetrated at Pulse were read out to the crowd.
The city held two vigils Sunday evening, one in Lakeview East and another in Andersonville.
New York City
At the Stonewall Inn, a downtown Manhattan landmark where, in 1969, the gay community pushed back against police raids and brutality, hundreds gathered for a vigil where participants waved anti-NRA signs and pride flags.
LGBT non-profit organization Indy Pride organized a gathering at the Old National Centre where mourners joined in a chorus of Leonard Cohen's Hallelujah.