The image below shows the INTELSAT-21 (IS-21) C Band western hemisphere beam signal strength over the continent. This is the satellite used to retransmit GNC-A data. The hotter the color, greater the signal.  As general guidance the closer to the equator and nearer to 58 degrees west longitude, the better the signal; not accounting for terrestrial interference, topography, and such. The very north western edges of North America, particularly at higher latitudes, will need to double check with Intelsat or a dish provider before investing in a smaller antenna. Similarly locations in the far eastern Caribbean may need to seek further guidance.

At the right side of the image, you may see the GEONETCast-Americas downlink characteristics, which you will have to use in order to configure the DVB-S/S2 receiver, like the NOVRA-S300D or the AYECKA SR1. More details on the Installation Manual and  the Equipment Guide.

Please find below the official high resolution coverage map provided by INTELSAT.