Keeping Track Of US visits

[cadvis]

I work in the US and travel each week few times back and forth. Does anyone know a easy way to track the entry and exit? Going out and coming in they do not stamp the passport. So it is very difficult to find when I left and when I came in. Any thoughts or ideas?

 

[CANUSA2013]

I keep an excel sheet with following columns with example .

Date In - Day & Time - Date Out - Day & Time - Location - PR Days - Citizen Days - Remarks

3/26/2013 - Tues 6 PM - 4/01/2013 - Mon 6 AM - VANCOUVER - 7 - 6 - TOOK LEAVE AND SPEND EXTRA LONG WEEKEND. TOOK KID TO SWIMMING ETC.