After filing I-90, can I go in and out of the U.S with my I-797?

USCIS states that before you travel, you should bring with you on any trip the temporary documentation you received. If after traveling abroad you try to reenter the United States with an expired Green Card, you may experience a delay during the inspection process at the port-of-entry. You can also contact USCIS directly about getting an extension on your green card while the application is pending. CITATION: Page 4. http://www.uscis.gov/sites/default/files/files/pressrelease/GreenCardRenewal_110702.pdf