If you have a United credit card you can enroll via the link above to have United donate 100 miles to the American Red Cross for every $1,000 that you spend between 3/15-4/15. There is no cost to you.
As a bonus for enrolling, United will also give you 100 miles without any spending required. The free miles will post by 5/31/17.
Don’t have a United card? You should and this post explains why. Aside from free checked baggage on all fares, free carry-on bags on economy basic fares, and priority boarding on all fares, you also get significantly greater saver and standard level award availability. It also waives the flight spend requirement to get elite status, gives 2 free annual club passes, and allows elites to get upgraded on award tickets. Plus the signup bonus is currently 55,000 miles instead of 35,000 miles!
You can view credit card offers by clicking on the “Credit Card Offers” tab on top of the DansDeals banner to view links for card offers. You can click on the link that says “View all card offers by issuing bank” and scroll down to view all card offers from the bank of your choice. Here’s How To View Credit Card Offers On This Site.