There are no restrictions as for domestic traveling while your Form I-485, Application to Register Permanent Residence or Adjust Status, is still pending. But there are strict rules regarding trips outside the United States, including trips to Mexico and Canada.
If you leave the United States while your application has not been approved yet, and you are applying for adjustment of status under INA section 245, USCIS will deny your Form I-485 unless:
- you are an H, L, V or K3/K4 nonimmigrant who is maintaining lawful nonimmigrant status and you return with a corresponding nonimmigrant visa that is still valid; or
- you obtain an advance parole document, by filing Form I-131, before you leave the USA, and you are paroled into the USA upon you return. Note that if you are filing Form I-131, Application for Travel Document, together with Form I-485 there is no need to pay any additional fee for an advance parole.
If you are applying for registry under INA section 249 and 8 CFR 249, you will also need to file Form I-131 and to obtain an advance parole document.
And if you are applying for adjustment of status under INA section 209 because you were admitted as a refugee or granted asylum, you may travel abroad and return to the United States with a refugee travel document obtained by filing Form I-131.
Meanwhile, in case you have immigration violations or criminal offenses consider not leaving the United States till the procedure is over and your Form I-485 is approved or consult an immigration attorney.