You can get up to 60,000 United miles by opening the airline's credit card, but the offer ends this week

Business Insider may receive a commission from The Points Guy Affiliate Network if you apply for a credit card, but our reporting and recommendations are always independent and objective.The United Explorer Card has one of its highest public sign-up bonuses, but it ends in just a few days.When you apply by May 16 — this Thursday — you can earn up to 60,000 United miles: 40,000 miles after spending $2,000 in the first three months, and another 20,000 miles after spending a total of $8,000 in the first six months.You can use the miles for anything from flights in economy to flights in Polaris business class, or even trips on Star Alliance partner airlines.For the past month, Chase has been running a promotion on the mainstream United Airlines credit card, which it issues. Sadly, all good things must come to an end: The limited-time bonus ends on Thursday, May 16.When you open a new card, you can earn up to 60,000 miles when you open a new card. The offer is broken into two chunks — you'll earn 40,000 United miles after spending $2,000 in the first three months, and another 20,000 miles after spending a total of $8,000 in the first six months.The United Explorer Card earns 2x United miles on purchases with United and at restaurants and hotels, and 1x mile on everything else.This sign-up bonus is one of the better public offers we've seen on this card, given the spending requirement, but it's only available until May 16.The card offers a free checked bag when you use your card to purchase your tickets. Since checked bags cost $30 each way, the value of this benefit can add up quickly — if you and another person on your reservation both take advantage of the free benefit, you'll save $120 on a round trip.The United Explorer Card also offers priority boarding as long as you have the open card attached to your MileagePlus account, 25% off in-flight purchases, and up to a $100 fee credit to cover your application to Global Entry or TSA PreCheck.The United Explorer also has two benefits that are unique among US airline credit cards in the same class.First, you'll get two complimentary one-time United Club lounge passes each year. In the lounges, you can enjoy comfortable seating, Wi-Fi, free food and drinks, and more before your flight. Normally, one-time entry to a United Club would cost $59 if you didn't have a membership.Second, although this is an unpublished benefit, United cardholders also get access to more saver award space than other United members — that makes it easier to find good flights when it's time to use your miles. It's unclear what will happen to this benefit when United switches to dynamic award pricing in November.The card has a $95 annual fee, which is waived the first year.Should I apply？This is one of the best public sign-up bonuses we've seen on this card, so if you're eligible to earn it, now is a great time to apply (there was an offer of up to 65,000 miles at the beginning of this year, but it had a higher spend requirement).Keep in mind that you won't be able to earn the bonus if you currently have the United Explorer Card, or if you've earned a sign-up bonus for this card within the past 24 months. You also may not be able to get approved if you've opened five or more personal credit cards in the past 24 months.Also keep in mind there are other cards that might be worth looking at if you fly United, like the Chase Sapphire Preferred Card.Note that we're focusing on the rewards and perks that makes this card a great option, not things like interest rates and late fees, which can far outweigh the value of any rewards.When you're working to earn credit card rewards, it's important to practice financial discipline, like paying your balances off in full each month, making payments on time, and not spending more than you can afford to pay back. Basically, treat your credit card like a debit card.Click here to learn more about the United Explorer Card from Insider Picks' partner: The Points Guy.