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tokens: ; Tiwari et al. 2019 ), and the hottest loops can live up to multiple hours (López Fuentes et al. 2007 ; Klimchuk et al. 2010 ). Most of the longest lived loops are probably a result of interaction of multiple loop strands, which sequentially heat making the loop bundle live much longer than a loop strand (e.g., Warren et al. 2002 ). Loop 23 in Table 1 shows this behavior of sequential heating (see the animation of Figure 1 ). The coordinates of the center of the box outlining the two footpoints for each loop are also given in Table 1 . For easy identification, the coordinates in bold font indicate that the surrounding box has unipolar magnetic flux; all others have mixed-polarity magnetic flux. We quantified the distribution of magnetic field strength and polarity at each foot of each loop via histograms of LOS magnetograms within the selected footpoint region, in the way presented in Figure 5 for three examples. We use a 6′′ × 6′′ boxed area centered at each foot to obtain LOS magnetogram histograms at each foot. The 6′′ × 6′′ size of the box ensures that the loop foot is completely covered within the box. We have three categories of loops: (1) loops with unipolar magnetic flux in both feet, (2) loops with mixed-polarity magnetic flux in both feet, and (3) loops having one foot in mixed-polarity flux and the other foot in unipolar magnetic flux. Of the 23 loops that we examined, ∼40% (9/23) have both feet in unipolar magnetic flux, ∼4% of loops (1/23) have both feet in mixed-polarity flux, and ∼56% (13/23) have one foot in unipolar and one in mixed-polarity flux. We have considered the presence of mixed-polarity only when the LOS magnetogram at the loop foot contains values ≥20 G of positive or negative minority polarity flux. The random noise level in the LOS magnetograms is about 7 G (Couvidat et al. 2016 ), fairly well below our selected lower limit. We would have counted footpoint 2 of our only category 2 loop as unipolar if there was no minority-polarity pixel with a negative B z value larger than 20 G, i.e., if there were no pixel in the second bin (in 20–40 G range, bin size is 20 G) on the negative/minority polarity side of the zero line in this footpoint box’s histogram in Figure 5 . This case is the most marginal one in our sample—in all other mixed-polarity cases there are several to many minority-polarity pixels with the magnitude of B z larger than 20 G. Because there is only one loop in the category of both loop-feet having mixed-polarity flux, in our discussions we often count it in the category of loops having at least one foot in mixed-polarity flux region. In Figure 2 we show three example loops, one from each of the three categories. In the top row of Figure 2 , we show an example loop that has both feet in unipolar magnetic flux (category 1); the peak time in the hot 94 image comes at 05:02:59 and the associated LOS HMI magnetogram is obtained at 05:02:52. The light curve for this loop in Figure 3 (a) also shows another