Currently, only Federal office building to straddle state line. Present Texas-Arkansas state boundary (established in 1841 by United States and Republic of Texas) passes through center. Each state had separate post offices until 1892, when first joint office was built on this site. It was razed in 1930, and in 1933 the present structure was completed. The base is of Texas pink granite while walls are of limestone from Arkansas. Recorded Texas Historic Landmark - 1970