Because the asphalt is black and darker colors absorb more heat and they get hotter faster, Where as sidewalk is not black. It still gets hot but it does not get as hot. The heat on the black asphalt transfers to your feet because it does not absorb all the heat
Though the speakers in both Okita's poem and Cisneros's short story have strong roots in foreign cultures, both of them feel more connected to their American identities.