How many times would I have to refill my gas tank for a road trip to Chicago?

I live in California near LAX. The car I would be using would be a 2004 Honda Civic Coupe I believe it has 33 mpg.

As many times as is necessary to get from one place to the other without running out of gas.

Don't expect to average 33mpg for the entire trip, and you won't be wise to run the tank nearly dry between refuelling. So expect to refill every 250 miles or so.

The Civic has a 50 litre tank so that's about 13 US gallons. If you averaged 30mpg you could actually go 390 miles between complete fill ups, but you'll be stopping more frequently than that for comfort and meal breaks and that's when you'll likely take the chance to refuel. At an average of around 60mph a stop every 4 hours would be realistic and many sources advise a break every 3 hours for safety. But a break every 4 hours is 240 miles so close to the initial estimate I gave of refilling every 250 miles.

If you fill every 240 miles then at an average 30mpg that's 8 gallons each time. On a 2000 mile trip that's 8 refills with about a third of a tank left over at the end. So budget for 64 gallons and a minimum of 8 stops.

If you drive for 8 hours a day, plus the comfort/refuelling breaks and manage an average of 60mph (it's actually likely to be less than that), you're realistically looking at a 4 day drive if you manage to drive for a bit over 8 hours a day, or more realistically you'll do the journey over 5 days. But if you have co-drivers then you may be able to do 12 to 16 hours a day and complete the trip much sooner.

Go to mal quest they can tell you and the route to take

Try gas buddy.com. Do not expect to get perfect rated mileage.
http://www.gasbuddy.com/TripCostCalculator
About 8 Fuel Fills would be the MINIMUM. There's no need to wait until near empty to refill the tank.
Your exact route and how you drive no one can guess.
You should take a break every few hours. Most use this stop for a toilet stop and maybe something to eat.
Using something like Gas Buddy you can find the cheaper stations along the way. You TOP up often.

It can be a long way between OPEN places on the prairies. Less than half full time to get some more.
No one can predict what scenic detours you might make. How much stuff you are hauling? Your tire Inflation? Using the Air conditioner and many other things that use up extra gas.
Saving a few pennies per gallon is not worth it if you run out and need to walk a mile to get a bit.
Add something at each stop.

If you have AAA membership you can get travel planing help for FREE.

Warning under 1/4 tank gauge is unreliable for exactly how much is left.

Perhaps if you told us the TANK SIZE skippy, we could give you an IDEA?!