It's a truism that history repeats itself -- that if you wait long enough, events remarkably similar to some that happened before will hit you right smack in the face.

This was shown again in the news article last week on crime problems that reported that the Crystal City area -- U.S. Rte. 1 south of the 14th Street bridges -- has statistically topped Arlington's tally every year but one since 1978. In that excepted year, Rosslyn was at the top.

Aha! Looking at history -- C.B. Rose Jr.'s "Arlington County, Va., a History" -- we find that in the 1880s "the areas around the Virginia end of the Long Bridge replaced by today's 14th Street bridges and the Aqueduct Bridge replaced by today's Key Bridge from Georgetown . . . became the stronghold of lawless elements" who bribed Arlington officials to maintain their gambling and vice activities.

"The unsavory characters who hung around these environs not infrequently resorted to violence. One locale near Rosslyn was known as 'Dead Man's Hollow' in which a body was reputed to be found on the average of once a week.

"Arlington farmers returning from selling their produce in Washington" -- and, I've read elsewhere, commuters well into this century who had to transfer between trolleys in Rosslyn -- "found it advisable to form an armed convoy in Georgetown before venturing through Rosslyn." Families whose kids went to school in Washington feared for their safety.

How the vice activity was smashed is a story for another day. But, frightening to some as things may now be on Washington's Virginia fringes, they seem far better than running the gantlet past Dead Man's Hollow of a century past. Signs to Spare

Metro must be keeping White House directional signs available as an off-the-shelf item for installation on the upper level of the McPherson Square station. On Tuesday, we reported that vandals had for at least the third time destroyed the sign, so useful to tourists. On Wednesday, a new sign had been erected. Last of the Seays

Speaking of Metro, for the first time in 45 years there's not a Seay -- pronounce that like plain "Say" -- on the active payroll of a local transit operator.

Millard C. (Blackie) Seay of Springfield joined the old Capital Transit Co. in 1940 and, through its successors, retired as a scheduling executive for Metro. Along the way his son Millard L. (Butch) Seay decided to follow his father's tire tracks (or, if you prefer, car tracks).

Until recently, 37-year-old Butch Seay was a member of a special Metro planning group. His dad reports that he's now gone to undertake the daunting task of heading the scheduling and planning office of the New York City Transit Authority.