Roundtrip Domestic Flights from Various US Cities under $99 on American & United (Travel Period Varies)

American and United both have plenty of domestic roundtrip flights pricing under $99.
Source: List of routes below taken from a Flight Baron email alert
Travel Window: Varies depending on route. Some have more availability than others. Now thru May 2018 is search range.
How To: Use Google Flights to search and use their Calendar feature to find the lowest priced fares. You can eliminate low-cost carriers from your search results by deselecting them in Google Flights. Alternatively, you can select United and American as the only results to show in your Google Flights search.
ROUTES:
ATLANTA (ATL):
Chicago (CHI) – $81
Miami (MIA) – $87
Philadelphia (PHL) – $79
AUSTIN (AUS):
Phoenix (PHX) – $94
BOSTON (BOS):
Chicago (CHI) – $89
Cleveland (CLE) – $89
CHICAGO (CHI):
Atlanta (ATL) – $81
Boston (BOS) – $89
Cincinnati (CVG) – $97
Dallas (DFW) – $89
Dayton (DAY) – $97
Houston (HOU) – $79
Fort Lauderdale (FLL) – $89
Los Angeles (LAX) – $95
Minneapolis (MSP) – $81
New Orleans (MSY) – $87
New York (NYC) – $79
San Diego (SAN) – $97
Washington DC (WAS) – $79
DALLAS (DFW):
Baltimore (BWI) – $96
Chicago (CHI) – $89
Cleveland (CLE) – $91
Denver (DEN) – $49
Los Angeles (LAX) – $79
Minneapolis (MSP) – $77
New Orleans (MSY) – $91
New York (NYC) – $87
Philadelphia (PHL) – $95
Phoenix (PHX) – $97
Pittsburgh (PIT) – $79
San Francisco (SFO) – $79
Tampa (TPA) – $79
Washington DC (WAS) – $96
DENVER (DEN):
Chicago (CHI) – $79
Dallas (DFW) – $49
Los Angeles (LAX) – $77
Miami (MIA) – $97
DETROIT (DTW):
Miami (MIA) – $75
Philadelphia (PHL) – $79
FORT LAUDERDALE (FLL):
Chicago (CHI) – $89
Houston (HOU) – $93
New York (NYC) – $93
HOUSTON (HOU):
Baltimore (BWI) – $99
Chicago (CHI) – $79
Los Angeles (LAX) – $79
Miami (MIA) – $89
Tampa (TPA) – $99
Washington DC (WAS) – $99
LAS VEGAS (LAS):
Chicago (CHI) – $95
Dallas (DFW) – $97
San Francisco (SFO) – $85
LOS ANGELES (LAX):
Chicago (CHI) – $94
Dallas (DFW) – $79
Denver (DEN) – $77
Houston (HOU) – $79
Minneapolis (MSP) – $79
San Francisco (SFO) – $84
Seattle (SEA) – $89
MIAMI (MIA):
Atlanta (ATL) – $87
Denver (DEN) – $89
Detroit (DTW) – $75
Houston (HOU) – $89
New Orleans (MSY) – $96
Washington DC (WAS) – $79
MINNEAPOLIS (MSP):
Chicago (CHI) – $81
Dallas (DFW) – $77
Los Angeles (LAX) – $79
Philadelphia (PHL) – $79
NEW YORK (NYC):
Chicago (CHI) – $79
Dallas (DFW) – $87
Miami (MIA) – $79
Minneapolis (MSP) – $97
Myrtle Beach (MYR) – $99
Orlando (MCO) – $99
PHILADELPHIA (PHL):
Atlanta (ATL) – $79
Dallas (DFW) – $95
Detroit (DTW) – $79
Fort Myers (RSW) – $85
Myrtle Beach (MYR) – $79
PHOENIX (PHX):
Austin (AUS) – $77
Denver (DEN) – $97
SAN FRANCISCO (SFO):
Chicago (CHI) – $99
Dallas (DFW) – $79
Las Vegas (LAS) – $85
Los Angeles (LAX) – $88
SEATTLE (SEA):
Los Angeles (LAX) – $89
WASHINGTON DC (WAS):
Chicago (CHI) – $79
Dallas (DFW) – $79
Dayton (DAY) – $97
Houston (HOU) – $99
Miami (MIA) – $84
Providence (PVD) – $97