To determine the utility of point-of-care ultrasound (POCUS) in detection of interstitial edema as a precursor to high altitude pulmonary edema (HAPE) by quantitative assessment of development of interstitial edema (as B-lines) in a healthy patient population at altitude. This was a cross-sectional, prospective study evaluating the development of pulmonary edema in healthy patients over a 96-hour period while at altitude of approximately 9,000 feet above sea level. A pulmonary exam consisting of four lung fields: bilateral lung apices (anterior/midclavicular at 3rd intercostal space) and bases (posterior axillary line at the 5th intercostal space) was performed by emergency physicians in four episodic 24 hour intervals. 48 patients were enrolled into the study. Overall, there was a statistically significant positive shift in B-line distribution from Day 1 to Day 3, with a negative shift in B-line distribution from Day 3 to Day 4. The shift was observed in both the lung apex and base (P<0.001 & P=0.004), respectively. The effect of participant age was also studied in a subgroup analysis. Both younger (less than 45 years old) and older (greater than 45 years old) populations had similar increases in B-line development within the first 3 days at altitude. However, the younger age group had a decrease in B-lines from Day 3 to Day 4 while the older age group continued to have a positive increase in B-lines. Our data indicates that POCUS can be used to document interstitial edema in patients at altitude in a variety of age groups. POCUS may be an used to detect patients at risk for developing HAPE.