Interestingly, CBP says it does not keep land crossing travel records..they only keep air and sea travel records:
https://help.cbp.gov/cgi-bin/customs.cfg/php/enduser/popup_adp.php?p_sid=undefined&p_lva=undefined&p_li=undefined&p_faqid=976&p_created=1167341280&p_sp=undefined
https://help.cbp.gov/cgi-bin/customs.cfg/php/enduser/popup_adp.php?p_sid=undefined&p_lva=undefined&p_li=undefined&p_faqid=976&p_created=1167341280&p_sp=undefined