Cheap flights from St. Louis to the United States from $31

In general, September is the cheapest month to fly from St. Louis to United States. Due to it being the ‘off-season’ during this time, you can expect flight prices to be around $322. If you aren’t able to travel during the month of September, then book flights to United States from St. Louis during October instead. Flights to United States in October, while not as cheap as those in September, still average around $332.

According to our data, Wednesday is the cheapest day to fly to United States from St. Louis. The lowest ticket price found for a Wednesday departure recently was $373. Keep in mind that prices can always vary depending on your route and whether or not you are flying domestic or international. If your travel schedule is flexible, try to avoid departing on a Sunday because tickets tend to average around $478. These prices are subject to change though, so be sure to set up a Price Alert for flights to United States.

The cheapest time of day to fly to United States is at noon when flights can be purchased for as low as $355. Try not to purchase tickets in the afternoon because they tend to be around $484. Of course, these prices can vary depending on the time of year and what airport you fly to.

Fly from Lambert-St Louis to Atlanta Hartsfield-Jackson for the best Lambert-St Louis - United States flight prices

You are more likely to see cheaper flights to United States from St. Louis when booking weeks ahead of your departure date. In general, you can expect to find flights to United States for around $348 when searching weeks out. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to United States from St. Louis for as low as $211 on momondo.

There are 4 cabin classes available to choose from on St. Louis to United States flights. Cabin price and availability will vary by airline so perform a search above to find the right deals for you.

Frontier, Southwest, and Delta are the most popular carriers operating from Lambert-St Louis to United States

Frontier, American Airlines and Southwest are the top three most popular airlines that fly to United States from St. Louis according to our data. Frontier is the first choice among our users, with 34% of people opting to fly with this airline when traveling to United States. Keep in mind that there are 9 different airlines that fly to United States on a routine basis, so you have a few additional options to choose from.

Historically, on average around 16% of flights between St. Louis and United States have experienced a delay on any given week. The average delay length over the past 12 months has been 127 minutes.

Generally, flights departing in the morning tend to experience fewer delays. Flights in the evening have, in the past, seen delays more frequently in comparison.

Wednesday is statistically the day of the week which experiences the fewest number of delays on this flight route. Sunday has historically seen more delays on average compared to the rest of the week.

According to our data, Southwest have had the least number of delays on this route over the last 12 months; with about 15% of their flights experiencing any sort of delay.

86 flights are operational daily from St. Louis to United States as of June 2026. The most popular departure time for this route is 6:00AM, with 47% of flights per day taking off at noon.

As of June 2026, 602 flights take off from St. Louis and land in United States each week. The most common flight departure day for this route is Fri, with 21% of weekly flights taking off on this day.