United Flight 4576 Deals & Information (2026/2027)

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United Flight 4576 Route Deals From $61

The cheapest prices found with in the last 7 days for return flights were $135 and $61 for one-way flights to Lambert-St. Louis Intl. for the period specified. Prices and availability are subject to change. Additional terms apply.

Sat, Sep 26 - Sat, Oct 3
ORD
O'Hare Intl.
STL
Lambert-St. Louis Intl.
$135 Roundtrip, found 1 day ago
$135
Roundtrip
found 1 day ago
Select United flight, departing Sat, Sep 26 from O'Hare Intl. to Lambert-St. Louis Intl., returning Sat, Oct 3, priced at $135 found 1 day ago
Fri, Oct 16 - Sat, Oct 17
ORD
O'Hare Intl.
STL
Lambert-St. Louis Intl.
$150 Roundtrip, found 1 day ago
$150
Roundtrip
found 1 day ago
Select United flight, departing Fri, Oct 16 from O'Hare Intl. to Lambert-St. Louis Intl., returning Sat, Oct 17, priced at $150 found 1 day ago
Sat, Sep 26 - Sat, Oct 3
ORD
O'Hare Intl.
STL
Lambert-St. Louis Intl.
$161 Roundtrip, found 1 day ago
$161
Roundtrip
found 1 day ago
Select United flight, departing Sat, Sep 26 from O'Hare Intl. to Lambert-St. Louis Intl., returning Sat, Oct 3, priced at $161 found 1 day ago
Thu, Sep 24 - Mon, Sep 28
ORD
O'Hare Intl.
STL
Lambert-St. Louis Intl.
$166 Roundtrip, found 1 day ago
$166
Roundtrip
found 1 day ago
Select United flight, departing Thu, Sep 24 from O'Hare Intl. to Lambert-St. Louis Intl., returning Mon, Sep 28, priced at $166 found 1 day ago
Sat, Sep 26 - Sat, Oct 3
ORD
O'Hare Intl.
STL
Lambert-St. Louis Intl.
$171 Roundtrip, found 1 day ago
$171
Roundtrip
found 1 day ago
Select United flight, departing Sat, Sep 26 from O'Hare Intl. to Lambert-St. Louis Intl., returning Sat, Oct 3, priced at $171 found 1 day ago
Thu, Sep 24 - Mon, Sep 28
ORD
O'Hare Intl.
STL
Lambert-St. Louis Intl.
$175 Roundtrip, found 1 day ago
$175
Roundtrip
found 1 day ago
Select United flight, departing Thu, Sep 24 from O'Hare Intl. to Lambert-St. Louis Intl., returning Mon, Sep 28, priced at $175 found 1 day ago
Thu, Sep 24 - Mon, Sep 28
ORD
O'Hare Intl.
STL
Lambert-St. Louis Intl.
$183 Roundtrip, found 1 day ago
$183
Roundtrip
found 1 day ago
Select United flight, departing Thu, Sep 24 from O'Hare Intl. to Lambert-St. Louis Intl., returning Mon, Sep 28, priced at $183 found 1 day ago
Thu, Sep 24 - Mon, Sep 28
ORD
O'Hare Intl.
STL
Lambert-St. Louis Intl.
$183 Roundtrip, found 1 day ago
$183
Roundtrip
found 1 day ago
Select United flight, departing Thu, Sep 24 from O'Hare Intl. to Lambert-St. Louis Intl., returning Mon, Sep 28, priced at $183 found 1 day ago
Sat, Sep 26 - Sat, Oct 3
ORD
O'Hare Intl.
STL
Lambert-St. Louis Intl.
$187 Roundtrip, found 1 day ago
$187
Roundtrip
found 1 day ago
Select United flight, departing Sat, Sep 26 from O'Hare Intl. to Lambert-St. Louis Intl., returning Sat, Oct 3, priced at $187 found 1 day ago
Fri, Sep 18 - Sun, Sep 20
ORD
O'Hare Intl.
STL
Lambert-St. Louis Intl.
$249 Roundtrip, found 11 hours ago
$249
Roundtrip
found 11 hours ago
Select United flight, departing Fri, Sep 18 from O'Hare Intl. to Lambert-St. Louis Intl., returning Sun, Sep 20, priced at $249 found 11 hours ago
Fri, Sep 18 - Sun, Sep 20
ORD
O'Hare Intl.
STL
Lambert-St. Louis Intl.
$253 Roundtrip, found 11 hours ago
$253
Roundtrip
found 11 hours ago
Select United flight, departing Fri, Sep 18 from O'Hare Intl. to Lambert-St. Louis Intl., returning Sun, Sep 20, priced at $253 found 11 hours ago
Fri, Sep 25 - Sun, Sep 27
ORD
O'Hare Intl.
STL
Lambert-St. Louis Intl.
$272 Roundtrip, found 17 hours ago
$272
Roundtrip
found 17 hours ago
Select United flight, departing Fri, Sep 25 from O'Hare Intl. to Lambert-St. Louis Intl., returning Sun, Sep 27, priced at $272 found 17 hours ago
Fri, Sep 25 - Sun, Sep 27
ORD
O'Hare Intl.
STL
Lambert-St. Louis Intl.
$276 Roundtrip, found 17 hours ago
$276
Roundtrip
found 17 hours ago
Select United flight, departing Fri, Sep 25 from O'Hare Intl. to Lambert-St. Louis Intl., returning Sun, Sep 27, priced at $276 found 17 hours ago
Fri, Sep 25 - Sun, Sep 27
ORD
O'Hare Intl.
STL
Lambert-St. Louis Intl.
$278 Roundtrip, found 17 hours ago
$278
Roundtrip
found 17 hours ago
Select United flight, departing Fri, Sep 25 from O'Hare Intl. to Lambert-St. Louis Intl., returning Sun, Sep 27, priced at $278 found 17 hours ago
Fri, Sep 25 - Sun, Sep 27
ORD
O'Hare Intl.
STL
Lambert-St. Louis Intl.
$282 Roundtrip, found 17 hours ago
$282
Roundtrip
found 17 hours ago
Select United flight, departing Fri, Sep 25 from O'Hare Intl. to Lambert-St. Louis Intl., returning Sun, Sep 27, priced at $282 found 17 hours ago
Tue, Sep 8 - Thu, Sep 10
ORD
O'Hare Intl.
STL
Lambert-St. Louis Intl.
$283 Roundtrip, found 8 hours ago
$283
Roundtrip
found 8 hours ago
Select United flight, departing Tue, Sep 8 from O'Hare Intl. to Lambert-St. Louis Intl., returning Thu, Sep 10, priced at $283 found 8 hours ago

Frequently asked questions

What route does flight number UA4576 take?
Flight number UA4576 operates non-stop from ACK to Newark, NJ Airport (EWR-Liberty Intl.). During this trip, you'll be in the air for approximately 1 hour and 40 minutes. Consider booking ahead to lock in your favorite seat.
What kind of plane is on flight number UA4576?
There's every chance you'll be cruising aboard the Canadair (Bombardier) Regional Jet 550 if you have a seat on flight UA4576. Typically, this flight leaves from Nantucket, MA Airport (ACK-Nantucket Memorial) and comes in to land at EWR.
If I am not able to travel due to COVID-19, can I change my flight to a later date?
For more info about changing your UA4576 flight with Travelocity, please visit our Customer Service Portal.